"I'm asking everyone to be a good citizen," Toronto Mayor Mel Lastman said. "Please don't leave garbage in the street if it's not being picked up by private contractors. Find a way to deal with it while we try and find a solution to the strike."

Nearly 7,000 workers walked off the job on Wednesday and another 17,000 - including public health nurses, social workers, lifeguards, ambulance dispatchers - could also strike this weekend.

If no agreement is reached, the strike is bound to smear Toronto's image as it hosts high-profile summer events.

"I am not going to predict (when this will end) because predictions in such cases are absolutely useless," Toronto Deputy Mayor Case Ootes said.

Andrea Addario, a representative of the Canadian Union of Public Employees, which represents the 7,000 striking workers, said both parts remained "quite far apart" on major issues, the most important one being job security.

Meanwhile, organizers of Toronto's Gay Pride parade, one of the biggest in North America, said they were finding private trash collectors to ensure that this weekend's celebration would not slide under layers of garbage.

The strike has also forced the cancellation of some Canada Day holiday events slated for Monday, including fireworks displays and a street festival.

Toronto residents produce nearly a million tonnes of trash a week, and Ontario Premier Ernie Eves said he will step in if the garbage problem becomes a health hazard.