A British woman who as a teenager ran away to join the ISIL (ISIS) group has lost a legal challenge aimed at restoring her citizenship.

The Special Immigration Appeals Commission in London ruled on Friday that Shamima Begum was not improperly deprived of her nationality, meaning she cannot return to London.

More:

Begum, one of three east London schoolgirls who travelled to Syria in 2015, resurfaced at a refugee camp in Syria last year and told reporters she wanted to return home.

But her apparent lack of remorse has triggered criticism in the United Kingdom.

Former Home Secretary Sajid Javid revoked her citizenship on national security grounds, but she challenged the decision.

British media reported that the action was taken on the grounds that she could obtain another passport because of her Bangladeshi heritage.

While Begum's parents are of Bangladeshi origin, she does not hold a Bangladeshi passport.

Some legal experts criticised Javid's move to strip her nationality, saying it left Begum stateless.

"Shamima Begum was 15 when she was groomed online, was born and grew up in Britain and has never been to Bangladesh," said Omar Khan, director of Runnymede Trust, a race equality think-tank.

"If she was called Sarah Brown she would never have had her citizenship stripped. She obviously remains British and not Bangladeshi, however Orwellian citizenship law and policy is."