Canadian carrier WestJet Airlines Ltd. canceled 235 Saturday flights after unionized mechanics went on strike late Friday, undermining government efforts to prevent travel disruptions during the busy holiday weekend.

The cancellations add to the 150 flights scrubbed on Friday and another 25 on Thursday, impacting more than 56,000 travelers at Canada’s second largest airline, WestJet said in a statement on its website. The airline plans to operate a “significantly reduced” schedule by the end of Saturday. 

The federal government had stepped in Thursday to prevent a strike by the Aircraft Mechanics Fraternal Association, with Labor Minister Seamus O’Regan directing the Canada Industrial Relations Board to impose final binding arbitration to resolve issues between WestJet and the union over labor talks. WestJet is controlled by Toronto-based private equity firm Onex Corp.

Despite the effort, the mechanics started striking Friday at 7:30 p.m. Toronto time, with the union citing a June 28 decision by the industrial relations board for permitting the labor action. O’Regan said Saturday in a social media post on X that he has reviewed the board’s decision, which he called “clearly inconsistent” with his direction, and will be meeting with the parties later on Saturday.