Jack Letts, also known as "Jihadi Jack", was reportedly stripped of his British citizenship.
The 24-year-old, who has dual nationality through his Canadian father John Letts and his British mother Sally Lane, left his home in Oxfordshire in 2014 to fight with so-called saying Islamic State in Syria.
The decision of the Home Office was first reported by Mail on Sunday and confirmed by ITV News sources.
ITV News understands that the decision was approved in the final days of Theresa May's administration, but the new Home Secretary, Priti Patel, had the opportunity to cancel her predecessor.
The Briton told ITV News in February that he was wanted to go home after being held for two years in a Kurdish prison – saying that he missed the comforts of British life, including pies and episodes of Doctor Who.
Jack told ITV News in the interview that he had freely joined the terrorist organization. He said: "It is for this reason that I said that people believe me terrorist … terrorist … it depends on your definition …" that of a man. .. "the bad thing to use.
"I understand … I was an idiot … As I said, I'm not trying to make myself innocent … by that definition, of course, I was a But that's not the life I want to lead now.It's not why I left … If I wanted to stay like an idiot … I would not have left. "
A Home Office spokesman said: "Decisions to deprive a dual national of citizenship are based on the wise advice of officials, lawyers and intelligence services, as well as all available information.
"This power is one of the means by which we can counter the terrorist threat posed by some of the most dangerous individuals and ensure the security of our country."
This decision was taken following a decision by the then Minister of the Interior, Sajid Javid, to deprive Shamima Begum, wife of the Islamic State, of his British nationality in February, after the 19-year-old traveled to a refugee camp in Syria before the group fell. – proclaimed territorial caliphate.
Ms. Begum was one of three girls from Bethnal Green, in East London, who had left the UK at the age of 15 in February 2015 and had returned in Syria to join the Islamic State.
Under international law, a person can be deprived of citizenship by a government only if it does not leave it stateless.