Union president Michel Parent, centre, leads public workers during a demonstration in Montreal on Wednesday. (Ryan Remiorz/Canadian Press)More than 5,000 Montreal blue collar workers staged a four-hour strike Wednesday to press the city for a new contract.

The workers, who have been without a contract since 2007, held a noisy protest outside city hall as talks with the city seem to be at a standstill.

It is the second time the workers have walked off the job in two months, but Mayor Gérald Tremblay continues to reject the union's demands.

The workers are asking for a salary increase of 10 per cent over four years. They are also demanding the city cut back on subcontracting to private firms.

Michel Parent says his union's demands are reasonable. (CBC)"I represent all the blue-collar workers on the island of Montreal," said Michel Parent, president of Local 301 of the Canadian Union of Public Employees.

"We have at least eight collective agreements already settled on the island of Montreal. It is the same demands that we have elsewhere that we have in Montreal, but we've reached an agreement elsewhere and not in Montreal simply because there is no will to reach an agreement in Montreal," Parent said.

Tremblay said the union's demands would cost the city more than $100 million a year.

"We will not give in," Tremblay said. "This is not something the citizens of Montreal can afford."

Tremblay said 65 per cent of the city's employees have already accepted the city's offer — a pay freeze for the first year, followed by a six per cent increase over the next three years.

Essential services, such as sewer repairs, were to be maintained during the job action, but delays were expected for garbage and recycling collection.