Montreal's blue-collar union, which sent a strike notice to the city late Wednesday afternoon, has been without a contract since August 2007. (CBC)

Montreal blue-collar workers will hold a one-day strike at the end of the month.

The union sent a strike notice to the city late Wednesday afternoon. The workers have been without a contract since August 2007. About 5,000 workers are expected to be off the job as of midnight on Aug. 31, which is the anniversary of the expiration of their contract.

Union president Michel Parent said the union has been waiting for the latest offer from the city since last June. The Canadian Union of Public Employees (CUPE), local 301 represents public workers in Montreal who deliver a range of services, including garbage collection and road maintenance.

'We're a little bit surprised at this moment because we reached an agreement last May with the pension fund.'—Jean Yves Hinse, Montreal's director of professional relations

Montreal's director of professional relations, Jean Yves Hinse, said the city is still waiting for all the union's demands before making a counter-offer, adding that he thought negotiations were going well.

"Yes we're a little bit surprised at this moment because we reached an agreement last May with the pension fund," said Hinse.

Parent said the union doesn't want to hold Montrealers hostage but he said it's time people are aware of how slowly negotiations with the city are proceeding.

Negotiations have been stalled over salaries and the use of subcontractors. Parent said the $355-million water metre contract the city signed with a private company is just the tip of the iceberg.

The union is asking for close to $100 million more than the city is offering. Parent said the union could hold a longer strike in the future if a deal isn't reached.

The union also sent notice of the strike to Quebec's essential services council, which was expected to meet on Thursday or Friday to rule on a list of services the union must deliver during the one-day strike.

Blue-collar workers in Montreal have not held a strike in 18 years. The average annual salary of a blue-collar worker is $42,000.