Passengers travelling by plane to, from or within Canada will soon have to undergo temperature checks before boarding as part of stepped-up airport screening measures meant to prevent the spread of COVID-19 by travellers, Prime Minister Justin Trudeau said today.

"Our government is mandating temperature screening for air passengers through a phased approach, first for those travelling to Canada, then for those travelling from Canada, and finally for those travelling within Canada," said Trudeau. "This screening will add yet another layer of protection."

Trudeau said any passenger who is found to have a fever will not be permitted to board a flight. Employees who work in secured areas of airports also will be required to undergo temperature checks.

The measure is necessary because it's not possible to maintain physical distancing on planes, which remains the best method for preventing the spread of the virus, Trudeau said.

Trudeau acknowledged that temperature checks only screen for one of COVID-19's symptoms — fever — and not for the illness itself.

"It is not the panacea," said Trudeau. "It is an extra layer of safety."

Temperature checks at airports will complement a number of measures already in place — including mandatory mask-wearing for all passengers and staff, enhanced cleaning protocols and physical distancing in airports.

Some Canadian airlines already have introduced temperature screening measures on their own. Air Canada became the first North American airline to do so on in May.

Privacy experts have warned it could breach privacy laws to ask for such sensitive personal information if it's unnecessary and not evidence-based.