WINNIPEG - The union representing aircraft machinists says Aveos Fleet Performance Inc., a company that provides aircraft maintenance to Air Canada, has shut down its plants in three cities, laying off more than 2,400 workers.

Tony Didoshak with the International Association of Machinists and Aerospace Workers says Aveos employees were given the notice simultaneously at 1:30 p.m. ET on Sunday in Montreal, Winnipeg and Vancouver.

The union, which also represents Air Canada's mechanics, baggage handlers and ramp personnel, had feared for Aveo's future after Air Canada moved to subcontract some of its work offshore.

Air Canada (TSX:AC.B) has moved maintenance of landing gear and engines out of Aveos facilities and is sub-contracting work to other maintenance providers, including to China. The airline has also delayed some work until the fall.

Air Canada is Aveos' largest customer, which provides about 90 per cent of its maintenance overhaul work.

Its exclusive contract expires in June 2013 and Air Canada has issued a request for proposals for future contracts.