A pregnant British teenager who ran away from Britain to join Islamic State extremists in Syria four years ago has said she wants to come back to London, but her path home is not clear.

Shamima Begum told The Times newspaper in a story published on Thursday that she is nine months pregnant and worried about the health of her unborn child.

'In the end, I just could not endure anymore,' she said, describing the death from illness and malnutrition of her first two children. 'Now all I want to do is come home to Britain.'

The 19-year-old Londoner was found by the newspaper in a refugee camp in northern Syria. She was one of three schoolgirls from the Bethnal Green neighbourhood who went to Syria to join IS in 2015 at a time when the group's online recruitment program lured a number of teenage girls to its self-proclaimed caliphate.

She told the newspaper she didn't regret joining the group and wasn't troubled the first time she saw the severed head of one of its execution victims — comments that will likely make it more difficult for her to convince British authorities she is ready to rejoin civilian society.

UK security minister Ben Wallace told Sky News it was 'worrying' that Begum did not express remorse. He said she would have known what she was getting into when she left London for Syria.

He said the British public would be concerned about someone returning to a country that 'they apparently hate' and stressed that 'actions have consequences'.

She told Times reporter Anthony Loyd that she had married a jihadi shortly after arriving in Syria.

British officials believe roughly 900 Britons went to Syria to join the extremists' cause. Of those, they believe around 20 per cent died and about half of the survivors have returned to Britain.