Shamima Begum, the British national who travelled to Syria as a schoolgirl to join ISIL (ISIS), has lost her latest legal attempt to regain citizenship.

The Special Immigration Appeals Commission – a tribunal that considers appeals against government decisions to remove citizenship on national security grounds – dismissed Begum’s appeal at a hearing on Wednesday.

She left London in 2015 aged 15 and, with two school friends, went to Syria, where she married an ISIL fighter and gave birth to three children, all of whom died as infants.

She was stripped of her British citizenship in 2019. Shortly after, she was found in a detention camp in Syria.

Begum, now 23, challenged that decision at a hearing in London last November.

Begum’s legal team accused the Home Office – the UK’s interior ministry – of failing to investigate whether she was a “child victim of trafficking”.

They said there was overwhelming evidence that Begum had been “recruited, transported, transferred, harboured and received in Syria for the purposes of sexual exploitation”.

Her lawyers also argued that she and her friends’ entry into Syria had been “facilitated by a Canadian agent working for ISIS”.

A book released in August last year investigating intelligence sharing between the UK, Canada and other allies alleged that the Canadian agent’s role in Begum’s case was later covered up by the police and Britain’s security services.

The Secret History of the Five Eyes by Richard Kerbaj, a former security correspondent of The Sunday Times, prompted demands for an official inquiry into Begum’s case. Canada and the UK declined to comment on the allegations, as is routine for security issues involving intelligence agencies.

Earlier, Begum’s lawyers claimed that then-Home Secretary Sajid Javid had “pre-determined” her British citizenship should be revoked in 2019 before receiving any evidence from officials, effectively rendering her stateless.

Javid argued at the time that Begum was a threat to national security. He also said she was eligible for Bangladeshi citizenship, the birth country of her parents.

Bangladeshi authorities said Begum did not have dual citizenship and had never visited the South Asian nation. They also ruled out granting her Bangladeshi nationality.

International law forbids countries from making people stateless by revoking their only citizenship.

Public opinion is divided over the case. Some say she should remain barred, while others believe she should stand trial in a British court for joining ISIL.