The first two cases of a particularly infectious coronavirus variant that recently emerged in Britain have been confirmed in Canada, health authorities said Saturday.

"The cases are a couple from Durham with no known travel history, exposure or high-risk contacts," Barbara Yaffe, acting chief medical officer for Ontario, said in a statement.

The couple have been placed in isolation, according to the statement, the same day that Ontario reimposed a lockdown for several weeks due to a spike in Covid-19 cases in the province since early December.

Canadian Prime Minister Justin Trudeau said Wednesday his country would prolong its suspension of passenger flights from the UK until January 6 in light of the coronavirus strain sweeping Britain.

The discovery of two cases in Ontario "further reinforces the need for Ontarians to stay home as much as possible and continue to follow all public health advice, including the provincewide shutdown measures beginning today," said Yaffe.

The lockdown in Ontario, Canada's most populous province at some 14 million residents, will last 28 days in the south of the region and 14 days in the north.

Private indoor gatherings outside the family circle are banned. Essential businesses, such as grocery stores and pharmacies, will be allowed to remain open, but restaurants will be limited to take-out or delivery service.

As of Saturday, Canada had recorded more than 534,000 cases of Covid-19 with more than 14,700 deaths.