Defence Minister Peter MacKay says it's unlikely the upcoming presidential runoff in Afghanistan will be free of election fraud, which derailed the original Aug. 20 poll.

Some countries have said the runoff, scheduled for Nov. 7, must take place freely and fairly in order for them to contribute more troops to the NATO-led mission there.

However, MacKay told CTV News Channel by phone on Sunday that an election free of vote-fixing may be out of reach.

"I think it's probably unrealistic to hold Afghanistan to that standard, particularly given the recent experience," MacKay said.

The original Aug. 20 vote ran into trouble after a United Nations-backed electoral complaints body reported evidence of widespread electoral fraud, eventually prompting the runoff.

"Clearly the fact that they're even able to hold an election as quickly as planned is admirable. It's an Afghan lead," MacKay added, referring to the fact that local police and armed forces will play a role in holding the upcoming vote.

MacKay made the comments after he attended a gathering of NATO defence ministers in Bratislava, Slovakia, last week. The theme of the meeting was the Afghan mission, he said.

Canada was not asked to contribute more troops to the mission during the meeting, MacKay said.

"That request never came."

But the ministers expressed "broad support" for a request by U.S. Gen. Stanley McChrystal to send tens of thousands of additional American troops to the central Asian country, according to the alliance's top commander, Secretary General Anders Fogh Rasmussen.

Meanwhile, ballots are already being transported to thousands of polling stations across Afghanistan in preparation for the second presidential poll in three months.

MacKay described the presidential election as a watershed event in the eight-year-old war.

"We have to have a government in place before we can go forward militarily, on the development side, on the governance side," he said. "So this is a critical tipping point in the mission."

There are fears that turnout for the runoff may be low, primarily because of security problems. As with the last election, the Taliban has threatened to attack anyone who casts a ballot.

About 24,000 polling stations were set up during the first vote. On Nov. 7, there will be only 16,000 stations, in an effort to minimize the risk of violence and fraud.

U.S. President Barack Obama is expected to delay a decision regarding McChrystal's request for more American troops until the runoff takes place.

Abdullah Abdullah, the candidate challenging President Hamid Karzai, has said that major changes are needed to ensure that the vote unfolds fairly.

"The environment should be different. It cannot be under the same rules and procedures," Abdullah said.