Prime Minister Justin Trudeau welcomed those fleeing war and persecution on Saturday even as Canadian airlines said they would turn back U.S.-bound passengers to comply with an immigration ban on people from seven Muslim-majority countries.

In pointed tweets a day after U.S. President Donald Trump put a four-month hold on allowing refugees into the United States and temporarily barred travellers from the seven countries, Trudeau said refugees were welcome in Canada.

"To those fleeing persecution, terror & war, Canadians will welcome you, regardless of your faith. Diversity is our strength #WelcomeToCanada," Trudeau said on Twitter.

A second tweet, also timed to coincide with outrage over Trump's immigration policy, included a 2015 photo of Trudeau welcoming a Syrian refugee at a Canadian airport.

Confusion abounded at airports around the world on Saturday as officials tried to interpret the new U.S. rules.

Trudeau's office said U.S. authorities had confirmed Canadian passport holders, including dual citizens from the seven countries, would not be affected.

Trudeau has walked a fine line with the Trump administration, avoiding direct criticism while promoting the progressive policies of his one-year-old Liberal government.

The prime minister would discuss Canada's immigration and refugee policies with Trump, Trudeau's press secretary, Cameron Ahmad, said. He did not say when that would be.

WestJet Airlines said it turned back a passenger bound for the United States on Saturday to comply with Trump's executive order but did not say which country the passenger had come from. Spokeswoman Lauren Stewart said the airline would give full refunds to anyone affected.

In the western province of Saskatchewan, Iranian doctoral student Mohammadreza Tayfeh found himself comforting the Delta Air Lines employee he called about a refund.

"I said, 'It's all right. It's going to be fine. Don't worry about it.' She was so upset," he said in an interview from Saskatoon.

Tayfeh, an engineering student living in Canada for seven years, had been invited to San Diego to meet with investors for his telecom business. While he had a visitor's visa, he missed the cutoff to travel by hours.

He decided not to risk flying from Saskatchewan in case he was detained on arrival in the United States. He said an Iranian friend who has been living in the U.S. and working at NASA for years was detained at the Doha airport in Qatar late Friday.

"You don't want to put yourself in that situation, to go there and they ask you questions and just deport you," he said.

In Vancouver, an employee at the American Airlines counter said one person travelling on an Iranian passport had been turned away Saturday morning.

Air Canada said it was complying with the order but did not comment on whether it had denied anyone travel.

A Porter Airlines spokesman said the Toronto-based carrier will be restricting passengers from travelling to the United States from the listed countries until further notice.