By . Arthur Martin . PUBLISHED: . 07:04 EST, 22 August 2013 . | . UPDATED: . 13:22 EST, 23 August 2013 . Counter terrorism police started a criminal investigation last night into thousands of secret intelligence files obtained by The Guardian newspaper. Scotland Yard said documents seized from David Miranda, partner of Guardian journalist Glenn Greenwald, contained ‘highly sensitive material ... which could put lives at risk’. Carrying documents that could be useful to terrorists carries a maximum ten-year jail sentence under the controversial Terrorism Act 2000. Challenge: David Miranda, pictured with his partner Glenn Greenwald, has won a bid to stop the British authorities from using the data they seized from him at Heathrow on Sunday . Officers who questioned the . 28-year-old Brazilian for nearly nine hours at Heathrow have now begun . an international investigation into how he was carrying ‘tens of . thousands’ of pages of material including secret files leaked by ex-CIA . analyst Edward Snowden. He . was travelling en route from Berlin to Rio de Janeiro on Sunday, on a . flight paid for by The Guardian, when he was stopped by police. His . partner Mr Greenwald has written several stories based on the documents . leaked from the US National Security Agency. After . Mr Miranda’s detention it emerged that David Cameron had explicitly . authorised the destruction of computers at The Guardian offices which . are believed to have held sensitive details. Challenge: Mr Miranda's solicitor Gwendolen Morgan outside the High Court in London . Victory: Ms Morgan outside court following the awarding of an interim injunction . The . police investigation is likely to explore whether Mr Miranda and . journalists at The Guardian were in breach of the Terrorism Act 2000. The law states that a person is committing an offence if he or she . collects or makes a record of information likely to be useful to a . terrorist. Last night Scotland Yard remained tight-lipped over whether detectives would be taking in journalists for questioning. Speaking . at the Edinburgh International Book Festival, Guardian editor Alan . Rusbridger said he did not know if he would be investigated. ‘It looks . like they’re mounting a criminal investigation into persons unknown,’ he . said. Asked about the . investigation, he said: ‘I don’t know anything about it. All I know is . that they’ve said they’re threatening to prosecute someone.’ Controversy: The Guardian's computer components, including the motherboard and solid-state hard drive destroyed in the interests of national security . Earlier . in the day the High Court heard that the Metropolitan Police had taken . possession of ‘tens of thousands of pages of material’ from Mr Miranda’s . electronic equipment. Judges . ruled that the security services could examine the seized material for . national security purposes and investigate whether Mr Miranda is a . person who is or has been concerned with the commission, preparation or . instigation of acts of terrorism. Jonathan . Laidlaw, QC, representing the Met, said the data contains ‘highly . sensitive material the disclosure of which would be gravely injurious to . public safety’. He . said the investigation was being carried out by counter terrorism . officers, but declined to give further details. ‘I am not prepared to . alert defendants here or abroad about the criminal investigation that . has begun,’ he added. Mr . Miranda’s lawyers had sought an injunction to prevent access to the . data, arguing his detention was unlawful and threatened ‘journalistic . sources whose confidential information is contained in the material . seized’. Row: David Cameron asked Cabinet Secretary Sir Jeremy Heywood to contact the Guardian about the classified material handed over by Edward Snowden, which led to the destruction of hard drives . It has been confirmed that Theresa May (pictured) knew that Mr Miranda would be detained . They said he had . had nine items, including his laptop, mobile phone, memory cards and . DVDs, taken during his detention on Sunday. Speaking . after the case Gwendolen Morgan, from law firm Bindmans, said the . Government now has seven days to ‘prove there is a genuine threat to . national security’. She added that she knew ‘very little’ about the . criminal inquiries. Last . night a police spokesman said: ‘The Metropolitan Police Service is . pleased that the High Court has rejected an attempt to prevent further . examination of material seized during the detention of a man under . Schedule 7 at Heathrow Airport. ‘We . welcome the decision of the court which allows our examination of the . material – containing thousands of classified intelligence documents – . to continue in order to protect life and national security. ‘Initial . examination of material seized has identified highly sensitive . material, the disclosure of which could put lives at risk.’ A . Guardian spokesman said: ‘It remains our position that David Miranda . was involved in legitimate journalistic activity. We have no details of . any criminal inquiry launched today and have not had any contact with . the police regarding this matter.’ The . Independent Reviewer of Terrorism Legislation has said he will examine . the use of anti-terror powers to detain Mr Miranda. David Anderson has . written to Home Secretary Theresa May to outline his reasons for looking . at the case. He said he wanted to establish if Schedule 7 of the . Terrorism Act 2000 was ‘lawfully, appropriately and humanely used’. Mr Miranda (pictured left with Mr Greenwald at a Brazilian airport) was questioned for nine hours by police .
Lawyers for David Miranda asked for High Court injunction against officials .
They hoped to stop Government examining data seized from 28-year-old .
Judges granted limited injunction allowing exemption for national security .
Police have started investigation of documents but must put it on hold .
Independent watchdog has launched investigation into his detention .
Miranda, the partner of Guardian journalist Glenn Greenwald, claims the nine-hour detention at the airport on Sunday was illegal .
By . Arthur Martin . PUBLISHED: . 07:04 EST, 22 August 2013 . | . UPDATED: . 13:22 EST, 23 August 2013 . Counter terrorism police started a criminal investigation last night into thousands of secret intelligence files obtained by The Guardian newspaper. Scotland Yard said documents seized from David Miranda, partner of Guardian journalist Glenn Greenwald, contained ‘highly sensitive material ... which could put lives at risk’. Carrying documents that could be useful to terrorists carries a maximum ten-year jail sentence under the controversial Terrorism Act 2000. Challenge: David Miranda, pictured with his partner Glenn Greenwald, has won a bid to stop the British authorities from using the data they seized from him at Heathrow on Sunday . Officers who questioned the . 28-year-old Brazilian for nearly nine hours at Heathrow have now begun . an international investigation into how he was carrying ‘tens of . thousands’ of pages of material including secret files leaked by ex-CIA . analyst Edward Snowden. He . was travelling en route from Berlin to Rio de Janeiro on Sunday, on a . flight paid for by The Guardian, when he was stopped by police. His . partner Mr Greenwald has written several stories based on the documents . leaked from the US National Security Agency. After . Mr Miranda’s detention it emerged that David Cameron had explicitly . authorised the destruction of computers at The Guardian offices which . are believed to have held sensitive details. Challenge: Mr Miranda's solicitor Gwendolen Morgan outside the High Court in London . Victory: Ms Morgan outside court following the awarding of an interim injunction . The . police investigation is likely to explore whether Mr Miranda and . journalists at The Guardian were in breach of the Terrorism Act 2000. The law states that a person is committing an offence if he or she . collects or makes a record of information likely to be useful to a . terrorist. Last night Scotland Yard remained tight-lipped over whether detectives would be taking in journalists for questioning. Speaking . at the Edinburgh International Book Festival, Guardian editor Alan . Rusbridger said he did not know if he would be investigated. ‘It looks . like they’re mounting a criminal investigation into persons unknown,’ he . said. Asked about the . investigation, he said: ‘I don’t know anything about it. All I know is . that they’ve said they’re threatening to prosecute someone.’ Controversy: The Guardian's computer components, including the motherboard and solid-state hard drive destroyed in the interests of national security . Earlier . in the day the High Court heard that the Metropolitan Police had taken . possession of ‘tens of thousands of pages of material’ from Mr Miranda’s . electronic equipment. Judges . ruled that the security services could examine the seized material for . national security purposes and investigate whether Mr Miranda is a . person who is or has been concerned with the commission, preparation or . instigation of acts of terrorism. Jonathan . Laidlaw, QC, representing the Met, said the data contains ‘highly . sensitive material the disclosure of which would be gravely injurious to . public safety’. He . said the investigation was being carried out by counter terrorism . officers, but declined to give further details. ‘I am not prepared to . alert defendants here or abroad about the criminal investigation that . has begun,’ he added. Mr . Miranda’s lawyers had sought an injunction to prevent access to the . data, arguing his detention was unlawful and threatened ‘journalistic . sources whose confidential information is contained in the material . seized’. Row: David Cameron asked Cabinet Secretary Sir Jeremy Heywood to contact the Guardian about the classified material handed over by Edward Snowden, which led to the destruction of hard drives . It has been confirmed that Theresa May (pictured) knew that Mr Miranda would be detained . They said he had . had nine items, including his laptop, mobile phone, memory cards and . DVDs, taken during his detention on Sunday. Speaking . after the case Gwendolen Morgan, from law firm Bindmans, said the . Government now has seven days to ‘prove there is a genuine threat to . national security’. She added that she knew ‘very little’ about the . criminal inquiries. Last . night a police spokesman said: ‘The Metropolitan Police Service is . pleased that the High Court has rejected an attempt to prevent further . examination of material seized during the detention of a man under . Schedule 7 at Heathrow Airport. ‘We . welcome the decision of the court which allows our examination of the . material – containing thousands of classified intelligence documents – . to continue in order to protect life and national security. ‘Initial . examination of material seized has identified highly sensitive . material, the disclosure of which could put lives at risk.’ A . Guardian spokesman said: ‘It remains our position that David Miranda . was involved in legitimate journalistic activity. We have no details of . any criminal inquiry launched today and have not had any contact with . the police regarding this matter.’ The . Independent Reviewer of Terrorism Legislation has said he will examine . the use of anti-terror powers to detain Mr Miranda. David Anderson has . written to Home Secretary Theresa May to outline his reasons for looking . at the case. He said he wanted to establish if Schedule 7 of the . Terrorism Act 2000 was ‘lawfully, appropriately and humanely used’. Mr Miranda (pictured left with Mr Greenwald at a Brazilian airport) was questioned for nine hours by police .
seized from David Miranda, partner of Guardian journalist Glenn Greenwald, contained ‘highly partner Glenn Greenwald, has won a bid to stop seized from him at Heathrow on Sunday . Officers international investigation into how he was material for . national security purposes and injunction to prevent access to the . data, arguing his detention was unlawful and threatened Service is . pleased that the High Court has