The prospect of a systemwide work stoppage by Air Canada's unionized flight attendants loomed large on Friday with a strike deadline just hours away, despite a government plea for the two sides to return to the bargaining table.

Air Canada said it remains available to continue negotiations with its flight attendants as it winds down operations ahead of a potential labor disruption.

The Montreal-based airline said labor negotiations with its 10,000 flight attendants are at an impasse and warned that the carrier may begin to shut down operations as early as Saturday without an agreement.