A major airline has issued an update amid disruption to travellers caused by a pay dispute. Air Canada had to scrap plans to restart operations on Sunday after the union representing 10,000 flight attendants vowed to ignore a return-to-work directive. The Canada Industrial Relations Board had ordered airline staff back to work by 2pm on Sunday following government intervention, with Air Canada initially planning to resume flights Sunday evening. Canada's biggest airline now says it will restart flights Monday evening, reports Bristol Live . Air Canada stated that the union "illegally directed its flight attendant members to defy a direction from the Canadian Industrial Relations Board". "Our members are not going back to work," Canadian Union of Public Employees (CUPE) national president Mark Hancock declared earlier on Sunday outside Toronto's Pearson International Airport. "We are saying no." The federal government did not immediately respond to requests for comment on the union's refusal to return to work. Mr Hancock claimed the "whole process has been unfair" and said the union would challenge what it branded an unconstitutional directive. "Air Canada has really refused to bargain with us and they refused to bargain with us because they knew this government would come in on their white horse and try and save the day," he said. The nation's leading airline announced early Sunday that the first flights would recommence later in the day, but warned it could take several days for operations to return to normal. The airline also cautioned that some flights may be cancelled over the next week to ten days until the schedule stabilises. Federal jobs minister Patty Hajdu intervened less than 12 hours after workers downed tools, ordering the 10,000 flight attendants back to work. She stated that now was not the time to gamble with the economy, particularly given the unprecedented tariffs imposed on Canada by the US. Ms Hajdu referred the work stoppage to the Canada Industrial Relations Board. The airline confirmed that the Canada Industrial Relations Board had extended the term of the existing collective agreement until a new one was determined by the arbitrator. The shutdown of Canada's largest airline early Saturday affected approximately 130,000 people daily. Air Canada operates around 700 flights per day. Aviation analytics provider Cirium reported that Air Canada cancelled a total of 494 flights on Sunday morning. This was on top of the hundreds of flights it had cancelled in the preceding days. The bitter contract dispute escalated on Friday when the union rejected Air Canada's previous request to enter into government-directed arbitration, which allows a third-party mediator to decide the terms of a new contract. Flight attendants downed tools at around 1am Eastern Daylight Time on Saturday. At the same time, Air Canada announced it would start barring flight attendants from airports. Ms Hajdu insisted that her Liberal government was not anti-union, stating it was obvious the two parties had reached a deadlock. Travellers whose flights were affected would be entitled to claim a full refund through the airline's website or mobile app, Air Canada confirmed. The carrier also pledged to provide alternative travel arrangements through other Canadian and international airlines where feasible. However, it cautioned that immediate rebooking could not be guaranteed as flights on other carriers were already at capacity "due to the summer travel peak". Air Canada and CUPE have been engaged in contract negotiations for approximately eight months, yet they have failed to secure a provisional agreement. Both parties have acknowledged they remain significantly divided on wages and the unpaid duties flight attendants perform when aircraft are grounded. The airline's most recent proposal featured a 38% rise in overall compensation, encompassing benefits and pensions, across four years, which it claimed "would have made our flight attendants the best compensated in Canada". However, the union rejected this, arguing the suggested 8% pay rise in the initial year was insufficient given inflation.