Plans by Canada Post to privatize its customer service call centres in cities across Canada are drawing fire from one of the country's largest unions.

The Public Service Alliance of Canada (PSAC), representing more than 165,000 public-sector workers, has pledged to combat the move, which is expected to result in the loss of 300 jobs across the country.

Call centres in Fredericton, Ottawa, Winnipeg and Edmonton are affected. The centres handle telephone inquiries from the public about postage rates and parcel tracking.

Canada Post's National Philatelic Centre in Antigonish, N.S., will also close, affecting about 70 jobs. The centre sells stamps from several other postal agencies around the world.

The Crown corporation said on Thursday that decreasing mail volumes prompted the cuts, which are slated to take place in 2011 after selected workers' contracts expire.

No full-time workers will be laid off, and the call centres will not be outsourced to overseas locations, a Canada Post spokesperson said.

In Manitoba, as many as 30 temporary employees at Canada Post's Winnipeg-based call depot will not have their contracts renewed. About 70 other permanent staff will move to other jobs with the Crown corporation.

Data for the other centres was not immediately available.

Privacy concerns raised

PSAC spokeswoman Janet May told CBC News that the changes are part of a broader effort by Canada Post management to move the company further toward complete privatization.

"Canada Post is in its 15th year of profit," May said. "So to an average Canadian, does it make sense that part of your postal system is getting privatized?"

The union said it also worries about the loss of people's privacy if they have to offer up personal information to a private company — especially if the call-centre work is outsourced to a U.S. company.

"I'm not sure that Canadians are ready to see their postal service become an information collection agency for the American government," said Robyn Benson, PSAC's executive vice-president for the Prairies.