Canada Post's urban workers could go on strike late Thursday night if the Crown corporation declines to accept its latest offer, as seven months of heated negotiations between the two sides appears ready to come to a head.

On Monday, the president of the Canadian Union of Postal Workers, Denis Lemelin, gave the required 72 hours notice that workers will walk off the job at one minute before midnight ET Thursday if a deal can't be reached.

Lemelin said the union is willing to continue talks right up to the strike deadline in order to finalize a new contract based on the terms of its final offer, which it submitted to Canada Post on Monday.

"After seven months of negotiations, Canada Post continues to demand major concessions, including unsafe work methods, a 22 per cent wage reduction for new hires and the elimination of a sick leave plan that members have had for over 40 years," Lemelin said in a news release.

"Canada Post's intransigence at the bargaining table has left the union with little choice but to accept unsafe and unfair conditions or strike. But we hope it won't come to that."

The union had previously reached an agreement with Canada Post that, in the event of a strike or lockout, workers will deliver government cheques, including Old Age Security and Child Benefit cheques, around June 20.

In a statement released Monday afternoon, Canada Post said the union has failed to consider issues the company is grappling with, including less mail to deliver.

"The latest counter offer from the union does nothing to address the significant challenges facing the company," Canada Post said.

Labour Minister Lisa Raitt urged the two sides to continue negotiating and expressed concern that a work stoppage would impact Canada's economic well-being.

"We are currently going through an economic recovery, which remains fragile," Raitt said in a statement.

Lemelin pointed out Monday that the two sides have been able to reach a last-minute agreement in past negotiations.

The union represents 48,000 full-time, part-time and temporary employees in its urban operations bargaining unit. The union's final offer contains several changes and amendments, including to its wage demands. It is proposing a wage increase of 3.3 per cent in the first year of the contract, followed by increases of 2.75 per cent in each of the contract's final three years.