TORONTO -- One of Canada’s biggest airlines has confirmed that three passengers who recently arrived in Toronto have tested positive for COVID-19.

WestJet said that the Public Health Agency of Canada informed the airline that one guest on board a Mar. 11 flight from London, England’s Gatwick Airport (WS 4) has tested positive.

The airline is advising guests, who were seated in rows 10-16 of WestJet flight 4, returning to Toronto Pearson Airport from London Gatwick (LGW),to self-isolate and call their own public health units.

WestJet went on to say that Canada’s public health agency told them that two other passengers who flew on a flight from Phoenix, Ariz. on Feb. 28 (WS1199) had tested also positive.

“Peel Public Health’s investigation has determined that the two cases may have been able to pass the virus to others during their return. Guests who were seated in rows 18-22 of WestJet flight 1199, returning to Toronto Pearson Airport from the Sky Harbor Airport in Phoenix on February 28, are directed to self-isolate and call Peel Public Health immediately.”

The news comes amid reports of lack of COVID-19 screening at Pearson Airport, despite an announcement on Friday which said the government was implementing new national measures to screen for the virus.

WestJet says that guests on both affected flights are being advised to “self-monitor” for signs of a cough, fever or respiratory issue.