Shamima Begum is set to appeal against a ruling that she cannot return to the UK to challenge the removal of her British citizenship.
Ms Begum was one of three east London schoolgirls who travelled to Syria to join so-called Islamic State (IS) in February 2015 and lived under IS rule for more than three years.
She was found, nine months pregnant, in a Syrian refugee camp in February last year, prompting then home secretary Sajid Javid to revoke her British citizenship later that month.
Last year, Ms Begum took legal action against the Home Office at the High Court and the Special Immigration Appeals Commission (SIAC), a specialist tribunal which hears challenges to decisions to remove someone's British citizenship on national security grounds.
In February 2019, SIAC ruled the decision to revoke Ms Begum's British citizenship did not render her stateless and was therefore lawful, as she was "a citizen of Bangladesh by descent" at the time of the decision.
A decision to revoke someone's British citizenship is lawful only if an individual is entitled to citizenship of another country.