Prime Minister Stephen Harper slammed Hamid Karzai following reports the Afghan president has threatened to quit politics and join the Taliban.

"I have not seen the context of President Karzai's remarks but what I have seen reported is completely unacceptable," Harper told reporters in Mississauga, Ont., on Wednesday.

"We have men and women who are over there putting their lives on the line to help the population in its struggle against the Taliban. These remarks are not helpful and in the context of the dangerous work that our people are doing they are completely unacceptable to Canada and I'm sure the same is true for all of our allies."

Earlier this week, Afghan lawmakers said that during a private meeting over the weekend, Karzai twice threatened to quit politics and join the Taliban if the West continued to pressure him to enact reforms.

People at the meeting said they thought Karzai's comments were aimed at hardline members of parliament.

U.S. officials said his comments were troubling and they threatened to cancel a planned Washington visit if Karzai didn't stop blaming the United States for his problems.

But on Wednesday, Karzai's spokesman denied reports that he made those comments.

Waheed Omar said Karzai's government had been shocked to see the comment appearing in media outlets and did not know where it came from.

There are 2,830 Canadians serving in Afghanistan. Since 2002, when the mission began, 141 Canadian soldiers have been killed. Four Canadian civilians have also been killed.