Video report by ITV News Correspondent Paul Davies
Jeremy Corbyn has told ITV News he questions the right of the home secretary to strip Shamima Begum of her British citizenship and he supports the IS bride's bid to return to the UK.
The Labour leader branded the government's decision a "very extreme manoeuvre" as he called for Ms Begum to "face a lot of questions" on British soil over her support of so-called Islamic State in Syria.
Mr Corbyn also called for the 19-year-old jihadi runaway, who gave birth to a baby boy in a refugee camp on Sunday, to receive "some support" from UK authorities.
Ms Begum was informed by ITV News on Wednesday of the Home Office's decision to strip her of her citizenship in spite of her family's appeal for help bringing the former London schoolgirl back home.
Asked about the case by ITV News Correspondent Angus Walker while meeting European leaders in Brussels, Mr Corbyn said: "She was born in Britain, she has that right to remain in Britain and obviously a lot of questions she has to answer but also some support that she needs."
He added: "She obviously has in my view a right to return to Britain. On that return she must face a lot of questions about everything she's done. And at that point any action may or may not be taken."
Questioning the right of Home Secretary Sajid Javid to intervene, Mr Corbyn said: "The idea of stripping anyone of their citizenship when they're born in Britain is a very extreme manoeuvre.
"Indeed I question the right of the home secretary to have these powers when the original law was brought in by Theresa May when she was home secretary."
Mr Javid fended off claims he has left Ms Begum stateless as he appeared on ITV News's Peston show on Wednesday night.
The home secretary refused to comment on individual cases but said: "I would not take a decision - and I believe none of my predecessors ever have taken a decision - that at the point the decision is taken would leave that individual stateless."
Mr Javid's comments came as Bangladesh refused the teenager dual citizenship.
Bangladesh's ministry of foreign affairs said Ms Begum was not a Bangladeshi citizen and had never even visited the country.
Ms Begum told ITV News she may pursue citizenship through the Netherlands having married a Dutch jihadi while in Syria.
More ITV News coverage of the Shamima Begum case: