OTTAWA - The head of Canada Post's union is calling for a meeting with the Crown corporation's CEO and a commitment that postal workers will be allowed to deliver critical mail such as social assistance cheques.

The union, which began one- and two-day localized strikes on June 3 but has decided against a national walkout so far, says it was irresponsible for Canada Post management to lock out its members on Wednesday.

"Today, all postal workers were ready -- the letter carriers as well -- to distribute the mail everywhere in the country," union president Denis Lemelin said Wednesday at a media conference.

"We were truly fulfilling our commitment to see to it that the public receives their mail."

Lemelin said the union wants to meet with Canada Post chief executive Deepak Chopra and called on him to commit to allow postal workers to deliver social assistance and other cheques.

Lemelin also proposed that Chopra reinstate the union's expired contract so that employees can return to work while negotiations continue.

"If Canada Post wants to have a collective agreement they have to give a new mandate to their negotiators, a real mandate to negotiate," Lemelin said.

The Canadian Union of Postal Workers, which represents about 48,000 workers, had targeted postal plants in Toronto on Tuesday for the first time since it began rotating strikes nearly two weeks ago. It also had a strike in Montreal for the second time since the walkouts began in Winnipeg on June 3.

Canada Post said late Tuesday that it would suspend all operations in urban centres across the country, saying the strikes have cost it about $100 million.

The postal service had already announced deliveries of letters and most parcels would be cut back to Monday, Wednesday and Friday due to a dropoff in volume since the strikes began.

The union has accused Canada Post of seeking to cause major disruptions in order to pressure the government into ordering workers back to work.

Labour Minister Lisa Raitt has tabled her intent to order striking workers at Air Canada back on the job, but hasn't done so with the postal workers.

Ottawa had appeared to rule out back-to-work legislation earlier this week, but the nationwide lockout could change that.

The federal government legislated striking postal workers back to work in 1997 -- the last time the union went on strike -- after they were off the job two weeks.

Canadians had already been feeling the effects of the labour dispute, not just from the rotating strikes, but because Canada Post had scaled back mail delivery in cities to Mondays, Wednesday and Fridays before declaring the lockout. The union had said the scaling back was an attempt by the corporation to provoke a general strike.

The current country-wide suspension of urban mail is likely to have a wider impact.

Although the labour dispute does not include rural postal workers, who fall under a different contract, even the post office has acknowledged that a prolonged lockout could mean they would eventually have no more mail to deliver.