A British teenager who joined the Islamic State group in Syria in 2015 said Wednesday she was shocked by a government decision to revoke her citizenship.
However, it is understood that both Begum's parents hold dual nationality with Bangladesh, while the 19-year-old is a British-born citizen.
"Please find enclosed papers that relate to a decision taken by the Home Secretary, to deprive your daughter, Shamima Begum, of her British citizenship", the letter reads.
The family said in a statement they were "disappointed" and were "considering all legal avenues to challenge this decision".
Ms Begum was 15 when she ran away from her home in London's Bethnal Green, part of a group of schoolgirls from the neighbourhood who went to Syria to marry IS fighters. "So they'd only have proof I didn't anything that is risky", she said.
Her lawyer argued she was stateless as she had only ever been a British citizen.
"I was hoping that maybe for the sake of me and my child they'd let me come back".
"British nationals have a right to come to the United Kingdom", he said, adding that "anyone who has put themselves in that situation can expect to be investigated and questioned and potentially prosecuted if they return to our jurisdiction".
Javid says he is relying on a section of the British Nationality Act 1981, which states that he can take away a person's citizenship "if the Secretary of State is satisfied that deprivation is conducive to the public good".
As her son was born before the move to deprive her of her citizenship, the child would be unaffected by the decision, Javid indicated. "People will be very concerned about the well-being of that child and that he will be exposed to her perverse views".
Britain stripped a teenager who travelled to join Daesh of her citizenship on security grounds, triggering a row over the ramifications of leaving a 19-year-old mother with a jihadist fighter's child to fend for herself in a war zone.
But security experts warned against letting the terrorist into Britain and the Home Office told her family on February 19, that Home Secretary Sajid Javid filed an order "removing her British citizenship".
She suggested she may now seek citizenship in the Netherlands, where her husband is from. "Now all I want to do is come home to Britain".
He told MPs that the step was never taken lightly, adding: "But when someone turns their back on the fundamental values and supports terror, they don't have an automatic right to return to the UK".
Leading politicians, including interior minister Sajid Javid, have vowed to prevent her return, pointing to her lack of remorse for joining the terror group.
The Home Office has declined to comment further on the letter.
The home secretary could tout the idea that Begum has the possibility of applying for a Bangladeshi passport in order to justify his decision.
Asked during the Sky interview if she felt she made a mistake going to Syria, Begum said: "In a way, yes".