Canada’s WestJet has cancelled more than 800 flights after mechanics walked off the job, upending the travel plans of thousands of people over the Canada Day long weekend.

Some 680 workers have been on strike since Friday after the Calgary-based airline and the Airplane Mechanics Fraternal Association (AMFA) failed to reach a deal on salaries and working conditions.

WestJet President and CEO Diederik Pen on Sunday apologised to travellers over the “unnecessary work stoppage”.

“I am encouraged by our employees’ willingness to rise above the adversity and deliver a safe and controlled operation going forward,” Pen said in a statement.

“We continue to hold our view that the current strike serves no purpose other than to inflict maximum damage to our airline and the country.”

WesJet has cancelled 832 flights since Thursday, more than half of them scheduled for Sunday.

The airline said its 180-plane fleet had been reduced to 32 active aircraft as of Sunday.

WestJet and the AMFA have each accused the other side of not negotiating in good faith.

The AMFA has argued its sought-after wage increase would cost WestJet less than 8 million Canadian dollars ($5.8m) beyond what the company has offered for the first year of their contract.

WestJet has said it offered a 12.5 percent wage rise in the first year of the contract, and a compounded wage increase of 23.5 percent over the rest of the five-and-a-half-year term.

The stoppage, which has disrupted the plans of some 110,000 travellers, went ahead despite a directive from Canadian Minister of Labour Seamus O’Regan on Thursday calling for a binding arbitration to settle the dispute.

In June, union members voted 97.25 percent to reject a tentative pay deal reached with WestJet.