Jobs Minister Patty Hajdu says the federal government is launching a probe into allegations of unpaid work in the airline sector as a strike at Air Canada stretches on.

Striking Air Canada flight attendants vowed Monday to defy another back-to-work order from Canada's labor tribunal, extending a work stoppage that has cancelled travel for half a million people worldwide.

More than 10,000 Air Canada flight attendants who went on strike early Saturday will be ordered to return to work by the Canada Industrial Relations Board (CIRB), according to a Saturday announcement by Canadian Jobs Minister Patty Hajdu.