Britain plans to revoke the citizenship of Islamic State bride Shamima Begum.

Her family's lawyer has told Sky News they are "disappointed" at the decision.

The 19-year-old has been trying to get back to the UK, after giving birth a baby boy in a Syrian refugee camp.

Begum has appealed for public sympathy and had drawn support from former New Zealand Prime Minister Helen Clark.

Clark believes the teenager was a child when she was radicalised and says Begum should be allowed back into the UK to face the justice system there.

READ MORE: Helen Clark weighs in on Isis teen bride's plea: 'She was groomed'

Begum she said she has no regrets about leaving her London home two years ago become an IS bride.

She was one of a group of schoolgirls from London's Bethnal Green neighborhood who went to Syria to marry IS fighters in 2015 at a time when the group's online recruitment program lured many impressionable young people to its self-proclaimed caliphate.

Though it is unclear whether Begum has committed any crime, her apparent lack of remorse has triggered criticism from many who believe her decision makes her a permanent pariah in Britain.

READ MORE: Andrew Dickens: Why we need to listen to Helen Clark

The head of Britain's MI6 security service, Alex Younger, previously warned that Britons returning from Islamic State are likely to have acquired "potentially very dangerous" skills and connections.

Though he didn't comment on the Begum case, Younger said that while U.K. nationals have a "right" to come home, public safety was the first priority.

Home Secretary Sajid Javid had previously told the Times he "will not hesitate" to prevent the return of Britons who "supported terrorist organisations abroad." But others have appealed for mercy, noting Begum's age when she fled.

Speaking with Mike Hosking on Monday, counter terrorism expert Will Geddes said the law is clear about giving statehood, to stateless Britons.

"This particular individual is in a position where she is entitled potentially to return to the UK, however, there will be many conditions around that."

However, he said the British government will be worried about opening the floodgates.

"About 800 Jihadi fighters that they have imprisoned over in Iraq and Syria are potientially going to be released and come back, or try to come back to the United Kingdom."

More to come.