Six suspected IRA terrorists thought to be behind a string of bomb attacks in Britain are facing new police probes after the Government withdraw controversial letters insisting they were no longer wanted. The fugitive paramilitary suspects had all received so-called 'comfort letters' under a peace deal negotiated by Tony Blair. telling them they could return to the UK without fear of being charged. But the letters only came to light last year after the collapse of the terror trail of IRA suspect John Downey, who was accused of murdering four soldiers in the 1982 Hyde Park bombing in London. Tony Blair negotiated a deal with Sinn Fein in which on-the-run terror suspects not wanted by police received 'comfort letters' The case against Mr Downey was thrown out after he produced a letter from the Government telling him he was no longer wanted and was free to travel to the UK. In the fall-out from the trail's collapse, Government ministers launched an inquiry into the letters – and insisted they were not 'get out of jail free cards' for terrorists. Following the Government's intervention detectives now believe these 'comfort letters' do not protect suspects from prosecution, documents leaked to the Telegraph reveal. The Police Service of Northern Ireland wrote to MPs on the Northern Ireland affairs select committee last week, revealing the major new phase in its inquiries into the 'on the run' cases. In the letter, Will Kerr, the Assistant Chief Constable, said the PSNI did not believe there was any barrier to prosecuting 'on the run' suspects who had been sent 'comfort letters' – because Coalition Government ministers have recently said the letters had no legal force. 'Whilst prosecutorial challenges may still lie ahead, the obstacles to investigating, arresting and charging suspects appear to have been removed,' Mr Kerr said. The PSNI will 'prioritise' re-examining the cases of 36 'on the runs' whose status was changed from 'wanted' to 'not wanted' during the scheme run by Mr Blair's government under which Mr Downey was mistakenly given a letter of assurance. It is understood that 'comfort letters' were given to suspects in the Harrods car bomb in 1983, which killed six and injured 90, and the Remembrance Day bombing in Enniskillen in 1987. Tony Blair said the peace process with Sinn Fein leader Gerry Adams (right) and Martin McGuinness would have collapsed without the letters . Other atrocities under investigation could include the Regent's Park bombing, in which seven military bandsmen were killed, on the same day as the Hyde Park bombing in 1982, and the 1984 Brighton bomb, which targeted the Grand Hotel where Margaret Thatcher's Cabinet members were staying, killing five people and injuring 34. It comes as MPs prepare to publish a year-long inquiry into the 'comfort letters' scheme. As part of the peace deal bringing an end to the conflict in Northern Ireland, IRA terrorists serving prison terms were let out of prison early. But this left the problem of fugitive terror suspects who had never faced trial. In a controversial agreement was reached between Mr Blair and Sinn Fein, police checks would be carried out and those who were no longer wanted would be sent a letter informing them of that fact. IRA terror suspect John Downey was wrongly sent an immunity letter . Mr Blair has insisted that only those individuals who were genuinely not wanted by police, and were therefore not going to face trial, were supposed to have received OTRs. He also insisted the scheme was 'not secret', even though leading Northern Ireland politicians, including Lord Trimble, who was First Minister of Northern Ireland from 1998 to 2002, and senior police chiefs in the province were unaware of it. For the past 12 months, MPs on the Northern Ireland affairs select committee have been investigating the on the run scheme. In a report to be published on Tuesday, the committee is expected to raise questions over whether the policy of sending 'comfort letters' to IRA suspects during Mr Blair's final months in office was lawful. Mr Blair has insisted the Northern Ireland peace process would have collapsed without the controversial scheme giving immunity from prosecution to republican terror suspects – the so-called 'on the runs'. The scheme, set up by the Labour government in 1999, assured more than 200 paramilitary fighters that they were no longer being hunted by the police. Some 95 recipients of the so-called 'comfort letters' were linked to almost 300 murders. Under hostile questioning from the Commons Northern Ireland affairs committee, Mr Blair refused to apologise for setting up a process which victims said effectively handed the recipients 'get out of jail free' cards. He told MPs: 'If I had been saying we are not dealing with this in any way at all… I think it is likely that the peace process would have collapsed,' he said. 'I wanted to put the death, destruction, terrorism and misery to an end. I couldn't bring back those people who had died during the Troubles but I was trying to make sure there would not be further victims.'
Fugitive paramilitary suspects had received so-called 'comfort letters'
'On the runs' not wanted by police were told they could return to the UK . Letters emerged in trial of Hyde Park bomb suspect John Downey . But the Government have insisted the letters do not provide immunity . The police have now confirmed they are probing six IRA suspects .