Canada's prime minister said Monday the singling out of a Ukrainian veteran alleged to have fought for the Nazis during World War II for a standing ovation during a visit by Kyiv's leader was shameful and intolerable.

The speaker of Canada's parliament, Anthony Rota, has apologised for the gaffe.

He had paid homage to Yaroslav Hunka, a 98-year-old Ukrainian immigrant, during President Volodymyr Zelensky's visit to Canada on Friday, telling the House of Commons Hunka had "fought for Ukrainian independence".

It was later pointed out that Hunka served in the 14th Waffen Grenadier Division of the SS, a Nazi military unit.

Prime Minister Justin Trudeau said this was "clearly unacceptable."

"This is something that is deeply embarrassing to the parliament of Canada and by extension to all Canadians," he told reporters.

A small faction allied with Trudeau's Liberals called for Rota to resign while the main opposition Conservatives slammed the Trudeau administration for failing to properly vet Hunka, despite claims it had no advance notice he had been invited to the event.

A Jewish advocacy group called the incident "shocking" and "incredibly disturbing".

Rota, a Liberal MP, apologised on Sunday, saying that he had "subsequently become aware of more information" which caused him to "regret" his recognition of Hunka.

"This initiative was entirely my own... I particularly want to extend my deepest apologies to Jewish communities in Canada and around the world," he said, repeating his comments on Monday in the House.