Air Canada said Wednesday that its largest union plans to strike as early as next week, potentially wreaking havoc for travelers during a usually busy school holiday.

The looming job action followed the workers' rejection of a tentative agreement signed by the International Association of Machinists and Aerospace Workers bargaining committee, following mediation. The union represents about 8,600 Air Canada mechanics, baggage handlers and cargo agents.

The union said a strike could start at 12:01 a.m. (0401 GMT) Monday, during a peak travel period coinciding with a one-week March break in classes that sees many Canadian students take vacation.

Air Canada executive vice president Duncan Dee said the strike notice will cause "uncertainty for thousands of our customers," but held out hope for a last-minute deal to avert a strike.

"We are hopeful that there remains sufficient time to avoid a work disruption," Dee said in a statement.

Air Canada has been the country's largest airline since it acquired competitor Canadian Airlines in 2001.

The airline's 3,800 customer service and ticket agents went on strike in June for just two days before getting an agreement for better retirement conditions under a threat of back-to-work legislation.

Its pilots and flight attendants also threatened to strike last year, separately.

The flag carrier is the 15th largest commercial airline in the world, serving 33 million customers annually.