TORONTO - General Motors Canada will slash its workforce by more than half by 2014 and close as many as 310 dealerships by the end of next year as part of a broad restructuring plan announced by the company Monday.

The troubled company's Canadian arm will reduce its hourly workforce by 57 per cent, from 10,300 currently to 4,400 over the next five years. The company employed 20,000 Canadians as recently as 2005.

Many of the 5,900 jobs being eliminated under Monday's latest streamlining plans were previously announced and include the closure of a truck plant in Oshawa, Ont., and a transmission plant in Windsor, Ont.

GM Canada spokesman Stew Low estimated that Monday's announcement will affect about 1,500 jobs on top of those already announced.

The announcement didn't surprise Canadian Auto Workers president Ken Lewenza.

"The reality is there's been significant plant closure announcements in Canada that are going to take place within the next couple years, and we're not totally surprised by the numbers although they're a little bit more than we'd anticipated," he said.

Lewenza said he expects most of the new job cuts will take place through attrition.

Meanwhile, a spokesman for the Canadian Automobile Dealers Association estimated that the dealership closures -- from 705 today to between 395 and 425 by the end of next year -- could affect as many as 12,000 Canadians.

"It's very significant and that reflects the market share decline they've been experiencing for a number of years now," said Michael Hatch, the association's chief economist.

The company said it also plans further cuts to its white-collar workforce.

The announcement by General Motors Canada came as its Detroit-based parent company General Motors Corp. (NYSE:GM) said it would cut 21,000 U.S. factory jobs by next year and phase out its storied Pontiac brand.

The company released its new restructuring plan after governments in Canada and the United States said its previous plan was insufficient for the company to receive long-term government aid. GM has until the end of May to get its new plan approved so it can continue receiving billions of dollars in government assistance.

GM Canada said the new plan will move "faster and deeper" than its previous one and will "speed the reinvention of the company's operations into a more customer-focused, leaner, and more cost-competitive automaker."

Tony Faria, co-director of the automotive research centre at the University of Windsor, said he expects governments will be happy with the new plan, and it would be unrealistic to ask GM to cut even more.

"GM has gotten itself very lean. It's hurt a lot of people, it's hurt all the workers who've lost jobs, it's hurt a lot of suppliers who have far less parts to supply to GM, and it's going to continue to hurt dealerships," Faria said.

"There's been a lot of suffering through all this, but hopefully the end result will be a smaller GM than can be quite profitable."

The company also said it plans "further discussion" with the Canadian Auto Workers and will likely ask the union to provide it with the same concessions it gave Chrysler in a deal ratified this weekend.

That deal cut Chrysler's labour costs by $19 an hour, while an earlier agreement between the CAW and GM cut its labour costs by about $7 an hour.

While neither agreement cut workers' base wages, the Chrysler agreement makes substantially deeper cuts to benefits.

Lewenza said last week the union is willing to talk to GM about the agreement it reached with Chrysler.

In a piece of good news, GM Canada will launch three of six new products at its Oshawa car plant and the CAMI joint-venture factory in Ingersoll, Ont., which the company runs with Japanese carmaker Suzuki.

These will include the Chevrolet Camaro, the Chevrolet Equinox and the GMC Terrain.

The Ingersoll plant currently produces the Pontiac Torrent, which will be phased out along with the rest of the Pontiac brand, but GM Canada said the Torrent would be replaced with the GMC Terrain.

But Lewenza said the elimination of the Pontiac brand will affect GM's St. Catharines, Ont., plant, which builds Pontiac engines, and could possibly speed up the closure of its Windsor transmission plant.

GM Canada currently employs 10,300 hourly workers and 2,000 white-collar employees at car and truck plants in Oshawa, a transmission plant in Windsor and an engine plant in St. Catharines. It also operates the GM-Suzuki joint-venture CAMI plant in Ingersoll.

The truck plant is slated to close May 14 and the transmission plant will close in 2010.