Canada, the major US ally in the war in Afghanistan, said Sunday that the war against the Taliban insurgents in Afghanistan cannot be won.

In an interview with CNN, Prime Minister Stephen Harper said: "We are not going to ever defeat the insurgency."

Harper, who has resisted pressure from the US to reconsider his deadline for withdrawal from Afghanistan by December 2011, said: 'My reading of Afghan history is that it is probably had an insurgency forever, of some kind.’

The most the Nato-led forces can accomplish, he said, is 'to have an Afghan government that is capable of managing that insurgency and improving its own governance'.

With Obama planning to send 30,000 more troops to Afghanistan soon, the Canadian prime minister said the US government must work out an exit plan for Afghanistan before asking for additional troops from its allies. He said he could comment on whether Canada would reconsider its proposed withdrawal from Afghanistan only after hearing 'strategy ...for an eventual departure' by the US.

Canada has more than 2,500 troops fighting the insurgents in Kandahar province of Afghanistan.

With more than 100 of their troops killed by the Taliban insurgents, most Canadians are not in favour of the country's presence in Afghanistan. Last year the nation's parliament set the December 2011 deadline to pull out of Afghanistan.