With just three weeks left until Christmas, Canada Post has cancelled its holiday delivery guarantee, saying the rotating strikes across the country have caused a significant backlog.

John Hamilton, a spokesperson for Canada Post, told CTV Ottawa the five weeks of rotating strikes among their workers have caused a backlog triple the normal holiday season and has forced them to cancel their holiday guarantee.

"We came into December overloaded,” he said. “We've been working through that but more and more comes and it's more than we're able to get out the door."

Hamilton also noted several “illegal” demonstrations across the country, including in Ottawa, Toronto and London, Ont., have further disrupted deliveries. Police in Ottawa made several arrests at a rally outside a sorting facility on Wednesday. Charges could include trespassing and mischief, officers say.

Canadian Union of Postal Workers, on the other hand, is calling the delivery delay a “manufactured crisis.”

"This backlog they had, I don't believe it was as extensive as what they're saying, the mail was still going out,” said CUPW Ottawa President Ian Anderson. “We should still be on rotating strikes. as far as I’m concerned.”

The union says Canada Post knew all along they could wait until the holidays and pressure the government to step in.

The federal government passed back-to-work legislation on Nov. 26 with the goal of salvaging the delivery schedule in time for the holidays. They now await the selection of a mediator-arbitrator, who then has 90 days to try and reach a contract settlement.

With a report from CTV Ottawa’s Mike Arsalides