One of Britain's most senior judges has called into question Sajid Javid's decision to strip Isil bride Shamima Begum of her British citizenship.
Jonathan Sumption, who retired as a justice of the Supreme Court in December, indicated that the Home Secretary may have breached international law by effectively making Ms Begum stateless.
Mr Javid claimed that Begum, 19, whose parents came to the UK from Bangladesh, was a Bangladeshi citizen under that country's law even though she had never been to Bangladesh.
This meant he could remove her British citizenship without making her stateless.
Speaking on the BBC's Reith Lecture today, however, Lord Sumption said: "I am frankly surprised at the suggestion that she can be regarded as the citizen of a country with which she has never had anything to do but that is the Government's position and I have no doubt it will be tested in the courts in due course."
The Bangladesh Government has rejected the British claim that she is a Bangladesh citizen and said it would refuse to accept her, although its nationality laws do include a right of “citizenship by descent” to anyone who is born to a Bangladeshi parent.
This right only lapses when a person reaches the age of 21.
Lawyers for Begum, who fled London to join Isil in Syria and married an Isis fighter with whom she had three babies, all of whom died, are however appealing the Home Secretary's decision.
Asked if the removal of citizenship also meant a person lost their standing under human rights, Lord Sumption said: "What they lose is their citizenship. That doesn't necessarily deprive them of their standing when it comes to human rights.
"I have no problem with the notion of depriving people of their citizenship who have gone abroad to fight in foreign wars save this.
"It's an established principle of international law that you cannot deprive somebody of his or her citizenship if the result would be to render them stateless.
"And whatever they may have done in Syria or anywhere else, that rule has always been applied and will no doubt be applied in this case."