WestJet said Thursday that it will suspend service to four Canadian cities amid slumping demand due to COVID-19 restrictions.

Starting March 19, the airline plans to suspend all flights to St. John's, London, Ont., Lloydminster, Alta. and Medicine Hat, Alta. until June 24. The cuts are the latest in a series of service reductions over the last few months, many of which have affected regional air routes.

"We have continued to operate in the face of uncertainty as domestic and international travel restrictions and quarantines have caused demand to plummet," WestJet president and chief executive Ed Sims said. "Unfortunately, with new and increasingly restrictive policies, we are left once again, with no other option than to suspend service to these communities."

Sims added that the company's ability to return service in certain market depends on the government's policies, including whether it prioritizes domestic travel for aid.

Flights between St. John's and Halifax will stop as of March 21 and flights between London and Toronto will be suspended on March 22, WestJet said. WestJet Link flights from Calgary to Lloydminster will end on March 19, and flights from Calgary to Medicine Hat will be suspended on March 21.

Canadian airlines have laid off thousands of workers this year and cut more routes as the federal government implements increasingly strict travel measures.

Air Canada's former CEO and president, Calin Rovinescu, said last week that talks between airlines and the government about sector-specific aid had accelerated recently, and that he expected the two parties could reach a deal soon.

Meanwhile, low-cost carrier Flair Airlines recently announced plans to expand its domestic service to eight cities in Canada, which will bring its number of domestic destinations to 18 by the summer.

Flair, which also added 13 new Boeing 737 Max planes to its fleet this year, said it is preparing for what it believes will be a restart of tourism and travel beginning in spring and summer.