OTTAWA - Canada's ambassador to Afghanistan is quoted as saying the corruption of the Karzai government made his "blood boil," in a diplomatic cable released Thursday by the whistleblower website WikiLeaks.

Ambassador William Crosbie offered that unvarnished assessment in his discussion last February with his U.S. counterpart, Karl Eikenberry.

The two diplomats were having a meeting in Kabul about the upcoming Afghan parliamentary elections and their views on Afghan President Hamid Karzai.

"In a frank discussion, Canadian ambassador Crosbie explained to ambassador Eikenberry that getting the electoral process right is a bottom-line position for Canada, and said we must be prepared for confrontation with Karzai on this issue, or risk losing credibility among our own population if we go along with a rigged election," said the cable, which was posted on the website of Britain's Guardian newspaper.

"Ambassador Crosbie told the ambassador that getting this right is a bottom line issue for the Canadians. He was emotional, saying the issue 'makes my blood boil,' as he described the Canadian view that the international community must stand up for the silent majority or be blamed for letting Karzai and his family establish across the country the system of patronage and control that exists in Kandahar."

Crosbie's perspective was hardly new. Western leaders have been blasting Karzai's administration over corruption for years.

But the cable offers new insights into the Harper government's underlying concern about the military sacrifice Canada is making on behalf of an unreliable government. It surfaces only weeks after Prime Minister Stephen Harper pressed Karzai on corruption at the NATO leaders' summit.

The cable was one of a series of new diplomatic notes made public by WikiLeaks that offered new details of corruption by the Karzai government, including purported links to his country's illicit drug trade.

The Conservatives and Liberals rallied Thursday around Crosbie, as the RCMP began hunting for the leaker of another memo that the Canadian diplomat wrote to Ottawa offering to resign because of the pending release of the WikiLeaks material.

The contents of a cable Crosbie sent to Foreign Affairs headquarters in Ottawa were published Thursday by two Canadian newspapers.

The newspapers said Crosbie feared his earlier comments about Karzai could damage Canada's relations with the leader. The ambassador reportedly offered to quit if that would help ease the situation.

A spokesperson at the Foreign Affairs Department in Ottawa confirmed Thursday the RCMP are investigating the source of the leak.

Earlier Thursday, Harper defended Crosbie.

Asked whether the ambassador went too far in his criticism of Karzai, Harper said: "Crosbie doesn't represent the government of Afghanistan, he represents the government of Canada in Afghanistan."

Harper, speaking in Mississauga, Ont., said it's well known that his government has been "outspoken in its concerns about some aspects of governance in Afghanistan."

The prime minister said Ottawa will continue to express those concerns "emphatically to our counterparts in Afghanistan."

Dominic LeBlanc, the Liberal defence critic, said: "Ambassador Crosbie is serving in one of the most difficult postings in the world and until we have reason to lose confidence, we think he should continue to do the important work he's doing."

In the Commons, NDP Leader Jack Layton asked why Canada was bothering to help a corrupt regime by keeping military trainers in Afghanistan for three more years.

"Why are the Conservatives training 300,000 soldiers for these guys? I do not get it," said Layton.

Foreign Affairs Minister Lawrence Cannon said both the governments of Afghanistan and Canada agree that corruption is "one of the major challenges" at play.

"Our government raises concerns regarding issues of democracy, human rights as well as the rule of law directly with the Afghan authorities and we expect our ambassadors to do exactly that," said Cannon.

Last month in Portugal, Harper said the Afghan government doesn't deserve a "dime" of direct foreign aid money until it deals with its widespread corruption.

Karzai asked NATO leaders and coalition partners to step up the flow of aid dollars directly to his government instead of filtering it through international organizations operating in the country.

The Afghan government receives 20 per cent of the billions of aid dollars directly, but Karzai wants to see that increased to 50 per cent.

Harper and fellow NATO leaders made it clear to Karzai during crucial talks on the future of Afghanistan that they want him to do more to weed out corruption, sources had told The Canadian Press.

U.S. President Barack Obama has said there are "real tensions" in the relationship with Karzai.