Shamima Begum’s return to the UK to challenge the deprivation of her British citizenship “would create significant national security risks”, the Supreme Court has heard.

Begum, now 21, was one of three schoolgirls from Bethnal Green who travelled to Syria to join the so-called Islamic State in February 2015 and became an IS bride before she was found in a Syrian refugee camp in February last year.

She has had three children while living in Syria, all of whom have died.

Her UK citizenship was revoked last year by Home secretary Sajid Javid on national security grounds.

The Court of Appeal in July permitted her to come back to the UK to pursue her appeal.

But Sir James Eadie, the QC representing the Home Office, told the Supreme Court today: “The exposure of the public to an increased risk of terrorism is not justifiable or appropriate on fairness grounds.”

He said: “She married an IS fighter, lived in Raqqa the capital of the self-declared ‘caliphate’ and remained with them for four years until 2019, when she left the last pocket of IS territory.”

He raised questions about a balance between her human rights and protecting the public from terrorism.

“Can it be right that a person who has involved themself in terrorism and now abroad and subject to restrictions... to insist on return to enable them to participate in such proceedings?

“Can it be right that they should be able to do so contrary to the most effective protection of the public from the risks of terrorism?”

Begum “presented a current threat justifying the removal of her British citizenship”, he told the hearing.

An MI5 assessment of the national security threat “concludes that individuals travelling to Syria to align with IS represent a serious and credible threat to UK national security”.

The Supreme Court is considering whether Begum should be allowed to return to the UK to appeal against being deprived of her citizenship and whether, if she is refused entry, her citizenship should be restored.

Begum’s barrister Lord Pannick argued that the Court of Appeal “correctly decided” that Begum should be allowed to return to pursue “a fair and effective appeal”. That would mean the order withdrawing her citizenship was “unlawful and must be set aside as it is far more serious than most criminal penalties”, he insisted.

Begum joined classmates Kadiza Sultana, 16, and Amira Abase, 15, all from Bethnal Green Academy, who quit their homes and families on February 17, 2015, to join IS. They boarded a flight at Gatwick to Istanbul, before making their way to Raqqa in Syria, following two months after another Bethnal Green Academy pupil, Sharmeena Begum (no relation), had gone to Syria.

Shamima Begum married Dutch convert Yago Riedijk 10 days after arriving in IS territory, with all three of her school friends also reportedly marrying foreign IS fighters.

She left Raqqa two years later 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 in the refugee camp.

The Supreme Court hearing concludes tomorrow (November 24) with judgement likely to be given at a later date.