The Dutch husband of Shemima Begum wants to bring her and their newborn child to live with him in The Netherlands.
Yago Riedijk, 27, joined ISIS when he was 15, and admits fighting for them, but despite being on a terrorist watch list in his native country he has not had his citizenship revoked.
Mr Riedijk is being held in a Kurdish detention centre in north-eastern Syria and faces six years behind bars if he returns home but in an interview with the BBC he claimed he rejected IS and tried to leave.
He married Ms Begum just 10 days after meeting her in IS territory and has also come out and defended the decision to do so despite her being just 15 at the time, and him 23.
Riedijk, from Arnhem, said he was initially uninterested by the prospect of marriage with the East London schoolgirl whom he met in a women’s centre but decided to marry her because it was ‘her choice’.
He said: ‘To be honest, when my friend came and said there was a girl who was interested in marriage, I wasn’t that interested because of her age, but I accepted the offer anyway.’
He added that she had seemed to be ‘in a good state of mind’.
He conceded ‘she was very young, maybe it would have been better for her to wait a bit’, before adding: ‘But she didn’t, she chose to get married and I chose to marry her.’
Local media in Arnhem said he was raised in a ‘lovely’ middle class family before converting to Islam and leaving for Syria in October 2014 to join ISIS.
Ms Begum is currently in limbo with the UK revoking her citizenship on the grounds that she is eligible for citizenship of Bangladesh through her mother, who is a Bangladeshi citizen.
However, Bangladesh’s ministry of foreign affairs has said that she isn’t a Bangladeshi citizen and that she will not be allowed into the country.
Ms Begum’s family last month told the Home Secretary they were going to challenge his decision to revoke her UK citizenship.
The IS fighter also told the BBC’s Quentin Sommerville that he was imprisoned in Raqqa and tortured after the extremists accused him of being a Dutch spy.
Ms Begum is now 19. As the IS caliphate crumbled she escaped the stronghold of Baghouz in Syria with her husband, she claims that she hasn’t seen him since then.
He reportedly surrendered to a group of Syrian fighters and his wife and new-born son ended up among 39,000 people in the al-Hawl refugee camp – it is said she has now been moved on from the camp.
Ms Begum and Riedijk have had three children together, two of which have died due to illness and malnutrition – a fact that has led Begum and her family to plead with UK authorities to let new-born Jarrah be raised in Britain for his own well-being.
The news comes as the town the pair fled from was yesterday the scene of a western-backed assault on ISIS fighters.
Syrian Democratic Forces (SDF) began the assault in Baghouz on Friday night after a pause in fighting to allow thousands of civilians to flee.
Fighters were backed by helicopters and drones as they closed in on the terror group’s last bastion close to the Iraq border.
Desperate IS fighters, many of them foreigners, used booby- traps in a last-ditch attempt to stop the crushing of their self-declared caliphate.
Mustafa Bali, an SDF spokesman, tweeted yesterday morning that heavy clashes were taking place as its forces advanced. ‘We expect it to be over soon,’ he said.
One SDF commander told The Mail on Sunday there were about 300 IS fighters – including some of its most hardened – still in the besieged area on the banks of the Euphrates river.
The fall of IS has been expected for weeks, but jihadis slowed the assault by using their network of tunnels and forcing civilians to become human shields.
Local sources claimed Western special forces were using rapid-hardening foam to trap those hiding in caves and tunnels.
Many of the jihadis’ tents appeared flattened and destroyed. Those escaping the enclave said food and medical supplies had dwindled, with some relying on a diet of ‘IS bread’ – leaves baked with animal feed.
Others said they had to eat animal droppings and sticks to survive.
Fighters captured over recent days include jihadis from France, Spain, Egypt, Kyrgyzstan and Tunisia.