Postal workers across Canada returned to work Monday, but they're not happy about it -- and members of the Vancouver local plan to demonstrate their frustration.

Lower Mainland posties will be gathering in front of the main Vancouver post office, located at 349 West Georgia Street, at noon to rally against the Harper government's back-to-work legislation.

The bill received royal assent late Sunday, setting the stage for the resumption of mail delivery on Tuesday.

It imposes wages lower than Canada Post originally offered before workers began rotating strikes that led to the full-scale lock out, which lasted two weeks.

Vancouver Local 846 president Robert Mulvin believes management of the Crown corporation had no incentive to reach a contract with workers because they knew the Harper government intended to impose an agreement.

Labour Minister Lisa Raitt told CTV's Question Period over the weekend that the government's intent was never to side with management, but members felt it was necessary to intervene.

The government gave unionized workers and Canada Post "a solution that is best for the economy," Raitt said.

But Canada Union of Postal Workers president Denis Lemelin called the back-to-work bill an attack on the right to free bargaining, and "really punitive to the worker."

He lamented that amendments proposed by the New Democrats were defeated. They included removing the salary terms that undercut the union wages originally offered by management.

The bill passed in the House of Commons on Saturday following the NDP's record-breaking 58-hour filibuster, which saw many MPs sleeping over on the Hill.

With files from The Canadian Press