A woman stripped of her British citizenship after travelling to Syria as a teenager to marry an Islamic State group fighter on Wednesday lost her legal battle to reverse the decision.

The ruling from Judge Robert Jay means that Shamima Begum, 23, cannot return to the UK from her current home in a refugee camp in northern Syria.

While the court determined that it was for the minister to make the decision, it also said that some of Begum's arguments had merit.

Begum was aged 15 when she left her east London home for Syria with two school friends in 2015. While there, she married an IS fighter and had three children, none of whom survived.

In February 2019, she said she was left stateless when Britain's then interior minister Sajid Javid revoked her British citizenship on national security grounds after she was found in the Syrian camp.

A UK tribunal ruled in 2020 that she was not stateless because she was "a citizen of Bangladesh by descent" at the time the decision was made by virtue of her Bangladeshi mother.

The UK Supreme Court last year refused Begum permission to enter the UK to fight her citizenship case. She subsequently took her case to the Special Immigration Appeals Commission (SIAC), which ruled on Wednesday.

In rejecting her appeal, Jay said "under our constitutional settlement these sensitive issues are for the secretary of state to evaluate and not for the commission".

There was, however, "considerable force" in Begum's arguments and that Javid's conclusion that she had travelled voluntarily to Syria "is as stark as it is unsympathetic", he added.

"Further, there is some merit in the argument that those advising the secretary of state see this as a black and white issue, when many would say that there are shades of grey."

Gareth Peirce and Daniel Furner, lawyers representing Begum, said the ruling meant "there is now no protection for a British child trafficked out of the UK".

They added that "every possible avenue to challenge this decision will be urgently pursued".

The interior ministry said it was "pleased that the court has found in favour of the government's position".

Begum could now appeal the decision by the Special Immigration Appeals Commission in the Court of Appeal. (AFP)