Fast food chain McDonald's maintains it is still in talks with the Unite union about scrapping controversial zero hour contracts, but the union says discussions have broken down.
Its competitor Restaurant Brands, which owns KFC, Pizza Hut, Carl's Jr and Starbucks, has agreed to end the contracts by July.
McDonald's says negotiations for a new collective employment agreement with Unite, a union that represents about 12 percent of its employee, include security of hours.
However Unite national director Mike Treen said the talks had broken down over the issue of zero-hour contracts.
He said Burger King and Wendy's were also refusing to drop the controversial contract.
The union is threatening to carry out what it calls "guerrilla style strikes" if they continue to refuse.
Mr Treen said it would start short 30-minute walk-offs in a week if agreements are not reached.
Kim Campbell of the Employers and Manufacturers Association said Restaurant Brands' agreement to scrap zero hours is due to skills shortages.
"Even relatively low-skilled jobs, it's difficult to get people who are reliable and qualified to do the work.
"Frankly, I think this is a good sign."
Mr Campbell said if zero hour contracts were required at all, sensible employers would work with staff and unions to come to agreement.