A woman who had her UK citizenship revoked after travelling to Syria to join the Islamic State group should be allowed to return home to challenge the decision, a court ruled Thursday.

Shamima Begum, 20, lost the first stage of her case about the legality of the government's decision at the Special Immigration Appeals Commission (SIAC) in February. But the tribunal also ruled she could not have a "fair and effective appeal" or play "any meaningful part" in the process, as she was living in a Syrian refugee camp.

Three senior judges at the Court of Appeal on Thursday upheld that SIAC ruling. "Ms Begum should be allowed to come to the United Kingdom to pursue her appeal albeit subject to such controls as the (home secretary) deems appropriate," they said.

Begum was 15 when she and two other schoolgirls from Bethnal Green in east London left home to join the jihadist group on February 17, 2015. She claims she married a Dutch convert soon after arriving in IS-held territory. She was discovered, nine months pregnant, in a Syrian refugee camp in February last year.

Her newborn baby died soon after she gave birth. Two of her other children also died under IS rule. The then-home secretary, Sajid Javid, annulled Begum's British citizenship on national security grounds after an outcry led by right-wing media.

That prompted her to take legal action, arguing the decision was unlawful, made her stateless and exposed her to the risk of death or inhuman and degrading treatment. The British-born Begum is of Bangladeshi heritage. But Bangladesh's foreign minister has said he would not consider granting her citizenship.

Her lawyer, Daniel Furner, said his client had "never had a fair opportunity to give her side of the story", which made the government's decision unjust. Human rights group Liberty also welcomed the decision, saying: "The right to a fair trial is not something the government can take away on a whim. It is a fundamental part of our justice system and equal access to justice must apply to everyone."

The Home Office called the ruling "disappointing" and said it would seek permission to appeal.