Video report by ITV News Security Editor Rohit Kachroo
Bangladesh's Foreign Minister has told ITV News that Shamima Begum is not his country's problem.
Abdul Momen said if she did go to Bangladesh after being stripped of her British citizenship she could be hanged for terrorism.
Shamima Begum was one of three schoolgirls to leave Bethnal Green to join the terror cult in 2015 and resurfaced at a Syrian refugee camp in March.
Now 19, Ms Begum was stripped of her British citizenship in February by Home Secretary Sajid Javid.
ITV News Security Editor Rohit Kachroo on the possible repercussions of Dr Momen's comments
The government's official reason for depriving Ms Begum of her British passport has never been made public, but it is believed that the fact her father was from Bangladesh meant she could be made a Bangladeshi citizen.
The comments from Bangladesh's chief diplomat on Thursday is the first official to respond on camera.
As well as firmly putting Ms Begum in British hands, Dr Momen told ITV News Security Editor Rohit Kachroo if she did go to Bangladesh she would be punished severely.
"We have nothing to do with Shamima Begum. She is not a Bangladeshi citizen," he said.
"She never applied for Bangladesh citizenship. She was born in England and her mother is British.
"If anyone is found to be involved with terrorism, we have a simple rule, there will be capital punishment. And nothing else.
"She will be put in prison and immediately, the rule is, she should be hanged."
It is against international law to make someone stateless.
The British government did not respond to Dr Momen's comments today, but in earlier statements, the Home Office have said that the someone could be deprived of their British passport "in order to protect the country, the Home Secretary has the power to deprive someone of their British citizenship where it would not render them stateless."
Dr Momen said Bangladesh had "zero tolerance" to terrorism and was a "model in eliminating all terrorists".
He said the Bangladeshi government were "supporting all other countries" in stopping the spread of terrorism.
The Foreign Minister added he would be "sad" if Ms Begum was left stateless, but said it "nothing to do with us".
"We see so many people who are stateless," he said.
He likened the British government's decision to strip Ms Begum of her British citizenship and potentially leaving her stateless to the treatment of the Rohingya by the Burmese authorities.
Bangladesh claims it is currently hosting almost 1.1 million Rohingya refugees after they fled over the border to escape persecution in their native country.
"When they're being persecuted and killed, we open our doors to save humanity. And for a temporary shelter for them.
"And they will be staying there, thanks to many governments, who have been supportive of us, providing some help."
Myanmar have agreed to take the dislocated people back once there are conducive conditions, Dr Momen said. Adding "and we trust them".