Shamima Begum cannot be “regarded properly at this stage as a victim”, the Home Office’s lawyers have told the Court of Appeal.

Ms Begum, now 20, was one of three east London schoolgirls who travelled to Syria to join so-called Islamic State (IS) in February 2015, and lived under IS rule for more than three years.

She was found, nine months pregnant, in a Syrian refugee camp in February last year, prompting then home secretary Sajid Javid to revoke her British citizenship later that month.

In February, the Special Immigration Appeals Commission (SIAC), a specialist tribunal which hears challenges to decisions to remove someone’s British citizenship on national security grounds, ruled that the decision was lawful as Ms Begum was “a citizen of Bangladesh by descent” at the time of the decision.

SIAC found that Ms Begum “cannot play any meaningful part in her appeal and that, to that extent, the appeal will not be fair and effective”, but ruled that “it does not follow that her appeal succeeds”.

Ms Begum’s challenge to the decision to refuse to allow her to enter the UK in order to effectively pursue her appeal was also rejected.

Setting out the Home Office’s case on Friday, Sir James Eadie QC said removing someone’s British citizenship was “a highly valuable weapon in the national security armoury” which was used to protect the public from “those who have been radicalised and those who are sympathetic to causes such as al Qaida and (IS)”.

Sir James said: “I fully accept that the position in relation to her (Ms Begum’s) degree of national security threat that she poses, whether or not she has truly recanted and whether or not she left of her own free will … are untested currently.

“But – and it is quite a big but – there has been an assessment by those who are expert and experienced in these matters and it has been considered appropriate and necessary to deprive in her case.”

Sir James said Ms Begum “went to Syria, she stayed there for four years, she offered herself to and married an (IS) fighter and she aligned, in that sense, with (IS)”.

He added that “why she did so” and what Ms Begum believed now were not known, but said “those bare facts bearing on her risk remain”.

Sir James said it would be “entirely wrong to approach this case on the basis that she is to be regarded properly at this stage as a victim”.

He added that Ms Begum may have now “recanted” her support for IS, but said: “Let us not forget that the attacker at Fishmongers’ Hall was at a seminar given by Cambridge University on rehabilitation.”

Convicted terrorist Usman Khan, 28, fatally stabbed Saskia Jones, 23, and Jack Merritt, 25, at a prisoner rehabilitation conference on November 29 2019 while out on licence.

Sir James pointed out that several people had been persuaded by the “sincerity of his (Khan’s) rehabilitation”.

He also argued that imposing an order under the Terrorism Prevention and Investigation Measures Act on Ms Begum in the UK would not be sufficient.

Sir James said that “the difficulty of that sort of suggestion … in the real world is graphically illustrated by the London Bridge killings” in 2017.

He said: “There was considerable monitoring of the individuals in the UK and yet they were able to … drive along the pavement at London Bridge killing the individuals that they did.”

Khuram Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22, killed eight people and injured dozens of others by using a hired van to plough into pedestrians on London Bridge before attacking people at random around Borough Market on June 3 2017.

Sir James concluded that Ms Begum was “deprived of her citizenship for proper and important national security reasons”.

Ms Begum’s lawyers argue that removing her British citizenship took away “the real possibility that she could return to the UK” and exposed her to “the real risk of removal to Bangladesh or Iraq”, where she would face extra-judicial killing or the death penalty.

Tom Hickman QC also pointed out that Ms Begum was only 15 when she left the UK, adding: “The only things that are clear are that Shamima Begum was a child when she left the UK and had been influenced to do so.”

Ms Begum was one of three schoolgirls from Bethnal Green Academy who left their homes and families to join IS, shortly after Sharmeena Begum, who is no relation, travelled to Syria in December 2014.

Kadiza Sultana and Amira Abase, then 16 and 15 respectively, and Ms Begum boarded a flight from Gatwick Airport to Istanbul, Turkey, on February 17 2015, before making their way to Raqqa in Syria.

Ms Begum claims she married Dutch convert Yago Riedijk 10 days after arriving in IS territory, with all three of her schoolfriends also reportedly marrying foreign IS fighters.

She told the Times last February that she left Raqqa in January 2017 with her husband but her children, a one-year-old girl and a three-month-old boy, had both since died.

Her third child died shortly after he was born.

At the conclusion of the hearing on Friday afternoon, Lady Justice King – sitting with Lord Justice Flaux and Lord Justice Singh – said the court would reserve its judgment and try to deliver it “as speedily as possible”.