Canadian Public Safety Minister Ralph Goodale confirmed on Sunday in a statement that Jack Letts, a British-Canadian man dubbed Jihadi Jack by the media and who has been behind bars in a Kurdish prison since 2017, has been stripped of his British citizenship.

"Canada is disappointed that the United Kingdom has taken this unilateral action to offload their responsibilities," a statement from Goodale said in a rare rebuke of Canada's ally.

A statement from the Home Office said revoking British citizenships is one way it counters terrorist threats. It said it does not comment on individual cases.

"Decisions on depriving a dual national of citizenship are based on substantial advice from officials, lawyers and the intelligence agencies and all available information," the statement said.

The man's parents are from Oxford and were found guilty earlier this year of sending him money. They received a suspended sentence.

Organic farmer John Letts, 58, and ex-Oxfam fundraiser Sally Lane, 56, said they were acting as any parents would have when they tried to send their son cash when he begged for help from another country.

They say they believed their son Jack Letts was in mortal danger and trapped in Raqqa, Syria.

Goodale said terrorism knows no borders, so countries need to work together to keep each other safe.

In 2015, Jack Letts posted on Facebook that he would like to perform a "martyrdom operation" on a group of British soldiers. Police warned the family that "sending money to Jack is the same as sending money to ISIS".

But by the end of that year, Jack Letts was indicating that he wanted to come home. The family tried to transfer more money but the funds were blocked and the couple was arrested.

Jack Letts, now 23, is being held by Kurdish authorities in northern Syria. His future is unclear.

Goodale said Canada is under no legal obligation to bring Canadians detained in Syria home. And he said they will not expose consular officials to undue risk.

Australian Associated Press