VANCOUVER - U.S. Ambassador David Wilkins warned NATO not to pull out of Afghanistan prematurely in comments that came just as MPs voted to extend Canada's military mission there for another two years.

But the American envoy could not say whether the U.S. military would step up if no other NATO country agrees to provide a 1,000 additional troops in the Kandahar region, where Canada faces continued Taliban attacks.

"It would be a mistake of epic proportions for members of the NATO mission to leave Afghanistan before its army and police are better prepared to defend the Afghan people,'' Wilkins told a business group here Thursday.

"It simply would be wrong in my opinion for those of us who enjoy the blessings of freedom to now abandon Afghanistan's 31 million people to the likes of the Taliban and al-Qaida.''

Pull out, Wilkins said, "and we'd find ourselves once again having to save a failed state from the clutches of terror using it as a base of operations.''

But he stressed Canadians will decide for themselves what the country's mission will look like after 2009.

Wilkins visited Canadian troops last year and spent Christmas with the Royal 22nd Regiment at a forward operating base.

"Our troops over there understand what they're doing over there is vitally important,'' he said.

The motion to extend the mission to 2011 passed easily in the Commons on Thursday afternoon -- 198-77 -- after the minority Conservative government reached a compromise with the Liberal Opposition.

The government motion is contingent upon NATO providing at least 1,000 troop reinforcements in Kandahar, and the military getting new helicopters and unmanned aerial vehicles.

Canada has been knocking on NATO doors and while a number of countries have begged off, U.S. and other NATO officials have suggested the condition, contained in former deputy prime minister John Manley's report, will be met.

But Wilkins gave no assurance U.S. forces would be used if no other NATO country offers troops.

"We're optimistic that one condition ... will be met,'' he told reporters. "But as far as any definite announcement or decision as to whose troops, I don't know if that decision's been made.''

Wilkins pointed out that the U.S. has already committed to send 3,200 marines and a contingent of helicopters to southern Afghanistan for a seven-month deployment, starting next month.

Some have speculated U.S. marines could fulfil the Canadian requirement.

"We just have to see what the future holds,'' Wilkins said.

"But we certainly have been supportive of Canada, and with Canada have been urging our NATO friends to step up to the plate and put more troops in Afghanistan.''

Wilkins stuck to familiar ground in his speech to the Washington-based Canadian-American Business Council, which was holding its annual meeting here.

He lauded the solid friendship between Canada and the United States and played down Canadian worries that a Democratic administration might try to scrap the North American Free Trade Agreement.

While Republican nominee Sen. John McCain backs free trade, Democrats Sen. Barack Obama and Sen. Hilary Clinton want the deal reopened, citing shortfalls in its environmental and labour components.

But NAFTA has become too closely entwined in the economic prosperity of both countries for anyone to risk revoking it, Wilkins said.

"No matter who wins the presidential election, I am confident he or she will look at the overwhelming evidence and understand that enhancing trade and productivity with our best friend in Canada is the right answer and we will always work it out,'' Wilkins said.

"Because that's what friends do.''

Wilkins also reaffirmed administration support for the 2006 Canada-U.S. Softwood Lumber Agreement, despite grousing in Washington over a split decision in a recent arbitration over purported Canadian violations.

"The agreement, as far as I am concerned, is working and we stand behind it,'' Wilkins said.

Montana Sen. Max Baucus, a Democrat and consistent Canadian nemesis on the softwood file, said last week Canada has consistently violated the agreement that ended five years of punitive lumber duties against Canada.