Air Canada CEO Mike Rousseau said on Monday the airline was "amazed" by the decision of its flight attendants' union to defy an order by the Canada Industrial Relations Board, which has declared the union's strike unlawful.

The strike is affecting about 130,000 travelers a day at the peak of the summer travel season, and the two sides remain far apart on pay and other issues.

Air Canada flights will resume on Saturday evening, as a strike by its 10,000 cabin crew came to an end. The Canadian Industrial Relations Board (CIRB) told the airline's staff to return to work and said that an expired collective agreement would be extended until a new one was agreed.