More than 10,000 Air Canada flight attendants will continue their strike despite back-to-work orders from the Canadian government, the Air Canada component of the Canadian Union of Public Employees said Sunday.

Canada’s largest airline now says it will resume flights Monday evening. Air Canada said in a statement that the union 'illegally directed its flight attendant members to defy a direction from the Canadian Industrial Relations Board.

The Canadian Union of Public Employees (CUPE), which represents roughly 10,000 flight attendants, called the federal directive “unconstitutional” and vowed to challenge it.