(Reuters) -Canada Post workers went on a nationwide strike on Thursday after the Canadian government called for the postal company to undergo a widespread transformation to bolster its finances and modernize operations, the Canadian Union of Postal Workers said.

"In response to the Government's attack on our postal service and workers, effective immediately, all CUPW members at Canada Post are on a nationwide strike," the union said.

Canada Post said that its operations will be shut down following the strike, and that its customers can expect delays.

"The corporation is disappointed that the union chose to escalate their strike activity, which will further deteriorate Canada Post's financial situation," the country's primary postal service said in an emailed statement to Reuters.

Earlier on Thursday, the Canadian government instructed Canada Post to begin major changes to its operations, saying that the company faces structural challenges, which - coupled with outdated restrictions and stalled negotiations between labour and management - have limited its ability to adapt, causing mounting losses.

"This situation is unsustainable. Canada Post is effectively insolvent, and repeated bailouts are not a long-term solution. Transformation is required to ensure the survival of Canada Post and protect the services Canadians rely on," the government said in a statement.

The government added that it is also reviewing the process for increases to the stamp rate.

The union said in a statement that the announcement made by the minister responsible for Canada Post, Joel Lightbound, gave no clear details about how changes would be implemented to the organization, and warned that the recommendations - which include community mailbox conversions, among others - could result in major job losses and changes to delivery standards.

CUPW said it was informed that Canada Post needs until next week to present new global offers.

In response to the strike, the Canadian Chamber of Commerce called for a return to the bargaining table for negotiations in good faith.