OTTAWA -- Transport Minister Marc Garneau says Canada's ban on flights from the United Kingdom will expire Wednesday when the clock strikes midnight.

Canada halted most air travel from the U.K., where a mutated strain of COVID-19 had been discovered, on Dec. 20.

New rules that require passengers returning from abroad to show proof of negative COVID-19 test results will prevent the spread of the virus across borders, Garneau said.

Passengers must take a PCR test -- the type of test common in Canada involving a deep nasal swab, and distinct from a rapid test. The test has to be administered less than 72 hours before takeoff, or 96 hours in the cases of two dozen countries, mainly in the Caribbean, Garneau said at a virtual press conference.

Airlines say they were not initially consulted on the testing scheme, which they will be responsible for enforcing at check-in counters around the globe.

Cabinet ministers appealed to Canadians to stay on home turf as coronavirus case counts reach new daily highs, and as some federal and provincial politicians take heat and lose jobs over holiday trips abroad.

"We strongly, strongly, strongly recommend to avoid all non-essential travel outside of Canada," said Foreign Affairs Minister Francois-Philippe Champagne.

"Canadians are understandably concerned and upset about these travellers," Blair added.

"There is not just a legal obligation but a moral one ... Lives are at stake. We have already lost far too many people."

Airlines and passengers have raised concerns about testing capacity in some countries, with the fear that some travellers could wind up stranded overseas.

"We consider that it is perfectly reasonable within 72 hours to get the PCR test and to get results," Garneau told reporters.

But Health Minister Patty Hajdu acknowledged that the requirement serves as a deterrent.

"This is exactly why we are advising people not to travel internationally," she said. "The reality is they may find it difficult even in countries that have the PCR testing capacity to acquire a test within the required timeframe."

This report by The Canadian Press was first published Jan. 6, 2021.