A mother has fled to Syria with her two young children to join Islamic State. Rehana Begum Islam abandoned her husband of 14 years, vanishing overnight with her eight-year-old son and three-year-old daughter. The 33-year-old travelled from Heathrow to Istanbul on February 14 and then took an internal flight to Gaziantep, a city on Turkey's border with Syria. She is believed to have been helped by a Syrian who was arrested last week on suspicion of getting three east London schoolgirls across the border. Runaway: Rehana Islam with husband Azizul and their two children, whose identities are protected . Her passport details were found on his laptop – showing she and her children have been with Islamic State fanatics for five weeks. Mrs Islam's devastated husband Azizul says he has not stopped crying since police revealed she had travelled to Gaziantep, a popular gateway to Syria for foreign fighters and jihadi brides. 'It's really hard for me,' said the 36-year-old minicab driver last night. 'I haven't seen my kids for more than one month. I can't even sleep without my kids. 'My question is why did she go there? She has two kids, she has a family, and this house is in her name. Why has she left everything? This is really unbelievable. 'When the police told me she travelled to Gaziantep – I've seen it in the news, so many British people are trying to travel there – it came into my mind that maybe she's gone to Syria but still I can't believe it.' Last night Turkish intelligence sources revealed her ID documents were found on the laptop of Mohammed al-Rashed. He was arrested on suspicion of helping Shamima Begum, 15, Kadiza Sultana, 16, and Amira Abase, 15, become jihadi brides in Syria. All three attended Bethnal Green academy in Tower Hamlets. Al-Rashed, 28, is said to have told detectives he has mainly helped British fighters but also South Africans and Australians. The details of two other Britons, aged 19 and 29, were on his laptop. Mr Islam said: 'He must've also helped her to get there. 'I'm worried about my kids, I hope she comes back with my kids. Please. She's going to destroy my two kids' lives. 'IS is killing Muslim people as well. My religion doesn't say anything about killing people. 'If you're Muslim you should know that the Koran doesn't say this. These people are dangerous.' Scroll down for video . Intelligence revealed Mrs Islam's documents were found on Mohammed al-Rashed's laptop, who  was arrested on suspicion of helping Shamima Begum, Kadiza Sultana and Amira Abase (pictured) become jihadi brides . The Bangladeshi-born father said he had no idea how his wife, who suffers from depression, had become radicalised. He did not know that the former RBS clerk posted frequently on Facebook about Islam. But he said she spent a lot of time on her smartphone. Mrs Islam took her laptop with her when she disappeared. Her husband added: 'If I knew anything I would do everything to stop my wife, especially my two kids. I do everything for my kids since they were born. I look after the kids like I'm their mother. 'I play the role of mother because my wife can't handle them sometimes. When I married her she wasn't religious, she was like a normal girl, she didn't even cover herself. But a couple of years ago she started covering up and praying five times a day.' Mr Islam, who works nights in Enfield, north London, said he suspected his wife was missing when he came home in the early hours. 'I couldn't see anyone in the house but most of the weekends she spends at her sister's house, it's not far, it's round the corner,' he said. 'I tried calling her big sister but she said she wasn't there. We called her friends, relatives and made phone calls, but no one knew so we called the police. 'The police told me she took a flight from Heathrow to Amsterdam, and from Amsterdam to Istanbul. When they found out that she flew to Gaziantep maybe then they thought she went to Syria. I don't have any clue.' Schoolgirls Kadiza Sultana, 16, Shamima Begum, 15, and  Amira Abase, 15, (pictured at Gatwick airport) fled to Turkey before crossing the border into Syria where they are believed to have become ISIS jihadi brides . Turkish intelligence sources said British authorities did not inform them that Mrs Islam might be travelling to Syria until February 23 – nine days after she landed in the country. Turkey has faced criticism for not controlling its border with Syria, but has accused European states in turn of failing to prevent would-be jihadists from leaving in the first place. There are increasing concerns about the growing numbers of young people being lured to the war zone in Syria and Iraq. Security services estimate that more than 600 Britons have gone to join militant groups since the explosion of violence in the region began. They include 22 women and girls who have travelled in the past 12 months, many of whom wanted to become jihadi brides.
Rehana Begum Islam has fled to Syria with son, eight, and daughter, three . She abandoned husband of 14 years and flew from Heathrow to Istanbul . Later fled across border into Syria and has been 'with fanatics for weeks'
Husband Azizul said: 'Why did she go there? She has two kids,  a family'