Airlines in the U.S. and Canada are pressing Justin Trudeau’s government for a plan to allow more flights, after a Canadian advisory panel said it’s time to loosen COVID-19 restrictions at the border.

The government should “clearly spell out how and when we will restart air travel between Canada and the U.S., with the objective of releasing the plan prior to June 21,” the National Airlines Council of Canada and Airlines for America said in a joint letter Friday to three Canadian cabinet ministers.

Airlines For America represents major carriers including American Airlines Group Inc. and Southwest Airlines Co. as well as cargo shippers FedEx Corp. and United Parcel Service Inc.

Last week, an advisory body set up by Trudeau’s government said it’s safe to begin relaxing rules in place for most of the pandemic that have decimated travel between the two countries.

Right now, most people entering Canada have to endure a 14-day quarantine, and those arriving through airports are supposed to spend as much as three days in an approved hotel while they wait for test results -- though hundreds have opted to skip the hotels and pay fines instead. The advisory group said fully-vaccinated travelers should be exempt from both quarantine and pre-departure virus tests and Canada should drop the hotel quarantine entirely.

Trudeau, however, has yet to outline a timeline for reopening, other than to say it will depend on cases and vaccination levels. About 60 per cent of Canada’s population has received one dose of a COVID-19 vaccine. Just 6 per cent have received two shots, but with vaccine supplies improving, the government has said all eligible Canadians will be able to be fully vaccinated by September.

“As vaccination rates increase exponentially in both countries, and provincial governments release their restart plans, now is the time for the federal government to engage immediately with airlines to deliver a clear roadmap and timeline to reopen the air border,” the airline groups said in the letter.

U.S. domestic passenger levels have rebounded to more than two-thirds of their 2019 levels during the last seven days, according to data compiled by the Transportation Security Administration. Internationally, Mexico continued to receive U.S. visitors during the pandemic and has become the most popular foreign destination by far for American travelers, according to Airlines for America.