Shamima Begum has lost the first stage of her appeal against the government's decision to remove her UK citizenship.
Ms Begum, now 20, left London in 2015, aged 15, to join Islamic State. She was found in a Syrian refugee camp in February 2019.
Former Home Secretary Sajid Javid
stripped her of her UK citizenship later that month.
A tribunal ruled that Ms Begum could be stripped of her nationality because she had not been left stateless.
The Special Immigration Appeals Commission (SIAC), a semi-secret court which hears national security cases, said she could instead turn to Bangladesh for citizenship.