Islamic State bride Shamima Begum, who fled to Syria aged 15, is not a Bangladeshi citizen and will be barred from entering the country, its foreign ministry has said.
The 19-year-old from London said she wanted to return to the UK with her newborn baby, with the end of the so-called caliphate in Syria imminent.
But Home Secretary Sajid Javid revoked her British citizenship in a move only permissible under international law if it does not leave the individual stateless.
There had been speculation that Ms Begum, who is of Bangladeshi heritage, may have citizenship there, but its minister of state for foreign affairs Shahriar Alam denied this on Wednesday.
A statement tweeted by the minister said: "The Government of Bangladesh is deeply concerned that she has been erroneously identified as a holder of dual citizenship shared with Bangladesh alongside her birthplace, the United Kingdom.
"Bangladesh asserts that Ms Shamima Begum is not a Bangladeshi citizen. She is a British citizen by birth and has never applied for dual nationality with Bangladesh.
"There is no question of her being allowed to enter into Bangladesh."
The statement added that Dhaka had only been made aware of the situation by the media.
Asked whether she had been left stateless by Britain, the Begum family's lawyer Tasnime Akunjee said: "It's certainly something we will be adding to the mix in terms of our appeal."
Asked about the situation on ITV's Peston, Mr Javid said: "I'm not aware of any Home Secretary in any party in any previous government that has taken a decision that would leave anyone stateless."
She was one of three schoolgirls to leave Bethnal Green to join the terror cult in 2015 and resurfaced heavily pregnant at a Syrian refugee camp last week.
Meanwhile, Mr Javid suggested the action to prevent Ms Begum returning will have no impact on her baby son's nationality.
Figures for 2017 show that 104 people were deprived of their British citizenship.
Australian Associated Press