Travellers to Canada will have to quarantine in hotels for up to three days under strict supervision and at their own expense, Prime Minister Justin Trudeau announced on Friday, citing concerns over new coronavirus strains.

Ottawa is also stepping up COVID-19 testing while Canadian airlines have agreed to cancel flights to sunbelt destinations until the end of April, Trudeau told a news conference.

"Now is just not the time to be flying," he said.

The extra measures come as public health officials are increasingly concerned about the spread of more transmissible COVID-19 variants, as well as an uptick in Canadians taking foreign trips of late.

Starting next week, all incoming flights to Canada will be directed to land at one of only four airports - in Montreal, Toronto, Calgary and Vancouver.

In addition to pre-boarding testing already required, travellers "as soon as possible in the coming weeks" will be given mandatory PCR testing upon arrival.

They will have to wait for those results at designated hotels for up to three days at their own expense, which Trudeau estimated will cost Can$2,000 (US$1,600).

If their test comes back negative, they'll be permitted to quarantine at home "under significantly increased surveillance and enforcement," Trudeau said.

Those with positive tests will be moved to a government quarantine facility.

Air Canada, WestJet, Sunwing and Air Transat, meanwhile, have committed to suspending flights to all Caribbean destinations and Mexico starting Sunday.

Non-essential travellers showing up at Canada's land border with the United States will also be required to show a negative test before entry.

Canada last March closed its borders to most non-essential travellers and required incoming travellers to quarantine for 14 days. 

But several provincial leaders have called on the federal government for stricter measures and enforcement after a recent spike in the number of Canadians taking winter vacations abroad.