Prime Minister Stephen Harper said he reluctantly decided to reconsider the plan to bring all Canadian troops home from Afghanistan next year because Canada is still needed in the war-torn country.

Speaking to CTV's Lloyd Robertson from the sidelines of the G20 Summit in Seoul, South Korea, Harper confirmed some troops will likely stay on after next year in a training capacity.

Previously, Harper had insisted that Canadian troops would be out by July but the opposition Liberals had suggested they would back an extended training mission.

"I haven't made a secret of the fact I'd like to see all our troops come home. But that being said when you look at the facts on the ground I think the reality is there does need to be some additional training of Afghan forces," he said.

Harper said the extended mission would be strictly non-combat, and would likely last from 2011 to 2014 because Afghanistan's troops have made progress but aren't yet ready to stand on their own.

"So I do this with some reluctance but I think it is the best decision when one looks at the options," he told reporters.

He said Canada has been in Afghanistan almost as long as the First and Second World Wars combined, and said the nation's sacrifice must be respected.

"We do want to make sure that as we leave, what we leave behind is a situation where the sacrifices Canadians have made -- and they have made a lot of sacrifices there -- that those sacrifices are appropriately honoured and we leave something of lasting benefit," Harper said.

Harper said many of Canada's NATO allies have made it clear they would like to see an extension of the combat mission, but he said that was never an option and the decision was made based on the facts, rather than diplomatic pressure.

According to some reports, the complement of soldiers staying on in a training capacity will be between 600 and 1,000.

Canada's combat mission is on schedule to end in July 2011.

The government would have to approve the training mission before it would go forward, and it appears the Conservatives have been laying the groundwork in recent days.

On Sunday, Defence Minister Peter MacKay suggested that a decision about an extended role for Canadian troops in Afghanistan could be made before Nov. 18.

NATO is due to hold a leaders' summit in Portugal on that date, and MacKay said the government may decide on Canada's future role in Afghanistan prior to that meeting.

On Monday, Harper's spokesperson, Dimitri Soudas, told CTV's Power Play that after 2011, "the government is considering the three following options: aid, development, and training in a non-combat role."

"The hard work that's been done by Canadian soldiers, diplomats and development workers will continue, but in a very different way," Soudas said.