Shamima Begum, the teenager who fled London to join Islamic State (IS), has said she only has "one citizenship" and it was wrong for the UK to revoke it without speaking to her first.
It is only possible to strip someone of their UK nationality if they are eligible for citizenship elsewhere.
It is thought Begum has Bangladeshi citizenship through her mother.
But the Bangladesh foreign ministry said the matter had nothing to do with the country.
The 19-year-old told BBC News she had hoped the UK would understand she made a "very big mistake" by joining IS.
She was a schoolgirl when she left Bethnal Green in 2015, and was found in a Syrian refugee camp last week after reportedly leaving Baghuz, IS's last stronghold.
She gave birth to a son at the weekend and now wants to return home.
While he said he would not comment on individual cases, Home Secretary Sajid Javid has suggested Begum's baby could still be British.
He told the Commons: "Children should not suffer. So, if a parent does lose their British citizenship, it does not affect the rights of their child."
Begum's mother is believed to be a Bangladeshi national which means under Bangladesh law she would be too.
But Begum told the BBC's Middle East correspondent Quentin Sommerville: "I wasn't born in Bangladesh, I've never seen Bangladesh and I don't even speak Bengali properly, so how can they claim I have Bangladeshi citizenship?”