Canadian Prime Minister Justin Trudeau's wife has tested positive for the new coronavirus, his office announced.

The statement on Thursday night said Sophie Gregoire Trudeau was feeling unwell and would remain in isolation. The first lady of Canada had returned from a speaking engagement in Britain and had mild flu-like symptoms, including a low fever, late on Wednesday night.

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"The Prime Minister is in good health with no symptoms. As a precautionary measure and following the advice of doctors, he will be in isolation for a planned period of 14 days," the statement added.

His office said the doctor's advice to the prime minister is to continue daily activities while self-monitoring, given that he is exhibiting no symptoms himself.

"Also on the advice of doctors, he will not be tested at this stage since he has no symptoms. For the same reason, doctors say there is no risk to those who have been in contact with him recently," the statement said.

The office said he would resume his duties on Friday.

Gregoire Trudeau also issued a statement thanking those who have reached out.

"Although I'm experiencing uncomfortable symptoms of the virus, I will be back on my feet soon," she said.

"Being in quarantine at home is nothing compared with other Canadian families who might be going through this and for those facing more serious health concerns."

Though self-quarantining himself, the prime minister is spending the day in briefings, phone calls and virtual meetings from home, including speaking with other world leaders and joining a special cabinet committee discussion on the coronavirus.

Trudeau spoke with US President Donald Trump and British Prime Minister Boris Johnson.

Personal message from Sophie. pic.twitter.com/rXVilM6dxH — Cameron Ahmad (@CameronAhmad) March 13, 2020

But Trudeau did cancel an in-person meeting with Canada's provincial premiers.

Opposition NDP leader Jagmeet Singh was also working from home after feeling unwell.

Singh said he had been in contact with a doctor and they do not believe he has the virus but was advised to limit contact with the public until he feels better.

Ontario, Canada's most populous province, is closing schools until April 5.

Quebec Premier Francois Legault is asking all people returning from travel abroad to self-isolate for 14 days.

The measure will be mandatory for all government employees.

He is also asking organisers to cancel all indoor events attracting crowds of more than 250 people and all other large gatherings that are not considered essential.

Alberta and British Columbia are also urging all events with more than 250 people be cancelled.

Canada has more than 140 confirmed cases, with one death - an elderly nursing home resident in British Columbia.