U.S. Secretary of State Hillary Clinton expects Afghan President Hamid Karzai to announce on Tuesday whether he will go ahead with a runoff vote, after a Canadian-led United Nations panel confirmed August's election was rife with fraud.

"(Karzai) is going to announce his intentions," Clinton told reporters Monday at the State Department. "I am going to let him do that, but I am encouraged at the direction the situation is moving."

The Electoral Complaints Commission released a report Monday, which indicated that the more than 995,000 problem ballots from the Aug. 20 vote had to be declared invalid due to fraud. That represents nearly one-third of the votes cast for Karzai.

After taking a sampling that was agreed upon with the Independent Election Commission, the UN-backed panel determined that the ballots in question "should be disqualified and invalidated," said CTV South Asia Bureau Chief Janis Mackey Frayer, reporting from Kabul.

"They have ordered the Afghan Independent Election Commission to do so and what it boils down to, is that people are believing that this is going to go to a runoff, that the incumbent President Hamid Karzai may be stripped of any clear win in this election."

International officials say the panel has determined Karzai no longer has the 50 per cent majority of votes required to secure an outright victory, meaning it is likely that a second election will be necessary -- one that will pit the incumbent candidate against lead challenger Abdullah Abdullah, the country's one-time foreign minister.

An independent calculation by Democracy International showed Karzai holding about 48.3 per cent support, after nearly 1 million of his votes were thrown out.

Preliminary results had previously shown Karzai with more than 54 per cent of the vote.

The U.S., Canada and other NATO countries are pressuring Karzai to go ahead with the runoff vote.

Prime Minister Stephen Harper spoke with Afghan President Karzai Monday afternoon, stressing that Canada expects fair and democratic elections in Afghanistan.

"I am told, (Harper) was very forceful in his comments to the president, saying, 'A lot of Canadians have lost their lives, Canadian troops are fighting on Afghan soil for democracy, not for a dictatorship,'" CTV Ottawa Bureau Chief Robert Fife said of the conversation between the two leaders.

The Prime Minister's Office did not reveal how Karzai responded to Harper but said the Afghan leader thanked Canada for its soldiers' contribution in his country.

Runoff concerns

A runoff election, however, would be highly problematic for the war-torn country.

"According to the Afghan constitution, that runoff would have to happen within the next two weeks," said Frayer.

"That poses a whole host of challenges: Security, logistics and the fact that winter is approaching here, so there would be a lot of people who simply wouldn't be able to make it to the ballot box again."

Afghan officials claim a runoff could be organized within two weeks, though that would still put the timing of the second vote very close to the onset of winter.

It is also unclear if the Independent Election Commission will accept the findings of the Electoral Complaints Commission.

Under Afghan law, the UN-backed panel is supposed to have final say on the matter, though Karzai's supporters on the Independent Election Commission say the partial recount goes beyond the normal complaint process.

Grant Kippen, the Canadian chairman of the Electoral Complaints Commission said he could not see a legal way for the Afghan panel to reject the results.

"Our decisions, our orders, are final and binding according to the law," Kippen said. "We've followed the law very clearly, very precisely. My sense is that the IEC is going to follow the law as well."

But Kippen said it was up to the Independent Election Commission to decide is a runoff was necessary.

Opposing views

Abdullah campaign spokesperson Fazel Sancharaki said the results of the fraud investigation were "a step forward."

"Now it is up to the IEC to announce the final results," Sancharaki said, suggesting that it wouold be illegal for the country's election commission to reject the fraud panel's findings.

Karzai spokesperson Waheed Omar said he did not think the public could "make any judgment based on the figures announced today."

Hundreds of pro-Karzai supporters held a protest in the southeastern city of Spin Boldak on the weekend, saying they would reject a second round of voting.

A runoff would also delay the arrival of additional U.S. troops to the country, whom the White House has said will not be dispatched until a credible government is in place. Canada has made similar statements.

"From a military point of view, there simply cannot be a sound assessment of any strategy going forward if nobody knows who's in charge," Frayer said.

With a report from CTV South Asia Bureau Chief Janis Mackey Frayer and files from The Associated Press