Mail delivery of letters and parcels across Canada is expected to be limited for the rest of the week due to rotating postal strikes in Montreal and Toronto — which handle 60 per cent of the country's mail.

"The combined impact of strikes in these areas is expected to result in major mail disruptions nationally on Tuesday, likely carrying over into Wednesday," Canada Post said in a statement.

The union announced Tuesday that 23 postal workers in Carbonear, N.L., Sioux Lookout, Ont., and Salmon Arm, B.C., will begin picketing at 11 p.m. ET as part of their ongoing labour dispute.

Despite the disruption to mail service, Federal Labour Minister Lisa Raitt suggested that back to work legislation is not yet an option. On Thursday, Raitt said the federal government is serving notice that it is willing to legislate an end to the Air Canada strike. But she said the two situations are different.

"In the case of Canada Post, we don’t have a national strike," she told CBC's Power & Politics. "What we have is a series of walkouts across the country depending upon what day of the week and where it is."

"It’s having an effect on the mail flow, but it’s not having a national significant effect at this point and time. But we’ll see what happens as it goes on."

Canada Post spokesman Jon Hamilton said the one-day strikes in Toronto and Montreal will have a "lagging" effect on the ability to deliver mail to urban centres nationwide.

"That's going to have a downstream impact across the country," he said. "Now it's really having an impact on our ability to operate."

About 15,000 postal workers walked off the job in Toronto and Montreal just before midnight, the latest targets of rolling strikes across the country.

The 24-hour job action in Canada's two largest cities comes as Canada Post said it has lost tens of millions of dollars since the rotating strikes began on June 2.

Sharply lower mail volumes were causing it to reduce most delivery services to three days a week in urban areas across the country, Canada Post said.

But the Canadian Union of Postal Workers, representing some 50,000 workers, accused the Crown corporation of trying to trigger a full strike by means of the service reduction in order to force the federal government to bring in back-to-work legislation.

Hamilton said the service has seen direct revenues drop by $65 million since the walkouts began.

"Unfortunately, the union's activities and the uncertainty caused by seven months of negotiations without resolution is chipping away at our business," Hamilton told CBC News. "We can't continue to take on those kinds of losses without reducing our costs."

Meanwhile, CUPW national president Denis Lemelin said Canada Post has effectively brought in a "partial lockout" by reducing delivery service to three days a week.

"Management is penalizing our members for exercising their right to strike," Gerry Deveau, CUPW national director for the Ontario region said in a statement released Monday evening.

"Reducing the work schedule to three days a week creates hardship for postal workers and their families," he said.

Lemelin insisted the rolling strikes have affected only about 30 per cent of the Canadian population so far, while plenty of mail in the system awaits delivery. The union chief also displayed photographs to reporters of full mail rooms that he said raised questions about Canada Post's volume claims.

"The government has to send them a clear message to sit and negotiate and maybe it will be a different ball game," he said. "About a general strike, we will evaluate the situation."

'For the union to pretend that the strike they're engaged in isn't having an impact on customers across the country is really dishonest.'—Jon Hamilton, Canada Post

In Ottawa, which has yet to hold a rotating strike, Canada Post's reduced-delivery move has prompted a group of postal workers to picket behind Westgate Mall.

The about 40 workers picketed in front of a distribution centre at the mall, saying that they want to work but the Crown corporation is keeping them out. They said they will stand on Carling Avenue handing out flyers to emphasize the union's position.

CUPW has offered to suspend its targeted walkouts if Canada Post reinstates the workers' collective agreement, which lapsed in January, but the Crown corporation has declined to do so.

'It ain't Christmas'

Hamilton said the agency would continue to staff based on volumes, which he insisted have taken a "huge hit" during the job action.

"For the union to pretend that the strike they're engaged in isn't having an impact on customers across the country is really dishonest," Hamilton said. "Anybody that's walked around the facilities and taken a full and honest look could see that it ain't Christmas these days."

CUPW has offered to suspend its targeted walkouts if Canada Post reinstates the workers' collective agreement, which lapsed in January. But the Crown corporation refuses to do so.

On the picket lines in Windsor, Ont., several striking postal workers said they were upbeat, despite the fact few signs of an agreement are on the horizon.

"Everybody's pumped," said one picket, who asked CBC News not to use his name over fears of repercussions from Canada Post.

"We want a contract. We want a negotiated settlement. We don't want to be on the picket line, but we have to do what we have to do sometimes."

When asked Monday what impact the rotating strikes have had, Lemelin insisted there has been a "big gain" since 10 days ago, when many Canadians were questioning what role mail delivery has in today's digital age.

"There's nobody asking that question anymore," he said.

Issues remain unsettled

Canada Post and CUPW held negotiations Saturday and into the night Sunday, facilitated by a mediator, but the two sides are still at odds on a host of issues, including new mail-processing technology the company wants to implement and wages for new hires.

On salaries, the union has said the parties are "fairly close" on wages for regular employees, but Canada Post is pushing for a significant cut in the hourly rate for new hires, to as low as $18 from about $23.

The union said Canada Post has been profitable for the last 16 years and is misrepresenting its financial position. It acknowledges first-class mail volume is down, but said that overall, it amounts to only a seven per cent dip since 2006.

The Crown corporation counters that measured on a per-address basis, mail volumes are down 17 per cent since 2006 and calls the union "out of touch" with the challenges facing the mail service.

"The uncertainty caused by seven months of negotiating and more than a week of union strike activity is hurting our customers, our employees and the business," Canada Post said in a written statement Sunday.

"We cannot support any effort by the union to delay this process further or entertain costly and unrealistic demands that would cause rate increases for the customers."

The union also said Canada Post should be looking at new ways to expand its business — by following the lead of many European postal systems and getting into financial services, for example, particularly in rural areas where big banks have closed their branches — instead of slashing its pay scales and workforce.

CUPW also denounced the withdrawal of employee medical benefits, saying some of its members are facing huge bills for medications that would have been covered by their drug plan.

Canada Post suspended its workers' health and dental coverage when the union issued its strike notice in May.

With files from The Canadian Press