Thousands of postal workers in Calgary and Edmonton will walk off the job Tuesday night as part of a rotating strike that has hit cities across the country.

The Canadian Union of Postal Workers says the strike will continue in the two cities for 24 hours, with 4,000 workers hitting the picket lines at 9 p.m. local time in Calgary and an hour later in Edmonton.

Gord Fischer, who is the national director for the CUPW's Prairie region, said that forced overtime often occurs in the two cities because of poor staffing.

"Canada Post is refusing to put proper staffing in place, leading to overwork and forced overtime," Fischer said in a media release. "Routes don't get covered and mail ends up sitting in the depots, leading to complaints about service."

He added that "the union has clear demands about improving our service and making sure adequate staffing is in place. Canada Post wants us to do more with less, regardless of what that does to the public's postal service."

Earlier, the rotating postal strikes hit Moncton, N.B., and Victoria for Tuesday, as Canada Post remained at odds with the union.

Five days into the strike, the two sides have yet to find much common ground. No meetings took place on Tuesday between the two sides.

Also on Tuesday, Jon Hamilton, a spokesperson for Canada Post, said the company is waiting for the union to respond to its latest offer.

"This generous offer is what's on the table, while the union continues their disruptive strike activities across the country," Hamilton said.

Union officials have said that there is a disagreement about pensions, staffing and the short-term disability plan in the next contract.

A statement posted on the Canada Post website on Monday indicated that the latest CUPW proposals "remain too expensive and fail to address the challenges facing the postal system."

Canada Post says that mail volumes are in decline, the post office faces greater competition and the public is increasingly using electronic services in lieu of traditional mail.

But the post office says the union "has not yet put forward an offer that could form the basis of a deal with Canada Post."

For now, postal workers are continuing to accept and process mail in all locations that are not in the midst of a rotating strike.

Rotating strikes have already occurred in Winnipeg, Hamilton and Montreal since the strike began last week.

With files from The Canadian Press