Afghanistan will hold a runoff election to determine a new leader of the war-torn country, after it was proven that the top-ranked, incumbent President Hamid Karzai did not gain enough votes to win the recent Aug. 20 election.

Independent Election Commission chairman Azizullah Lodin said Tuesday that the commission did not want to "leave the people of Afghanistan in uncertainty" any longer.

"The commission is agreed to go to a second round and say that nobody got more than 50 per cent," Lodin said.

Under Afghan law, a runoff election is required if no candidate garners more than 50 per cent of the total votes. It is expected to take place within two weeks.

Reporting from Kabul on Tuesday, CTV South Asia Bureau Chief Janis Mackey Frayer said Nov. 7 is the target date for the runoff election.

The formal decision to hold a runoff came one day after the UN-backed Electoral Complaints Commission announced that nearly one-third of the ballots cast for Karzai had to be thrown out because of fraud.

An Afghan source close to Karzai told Then Associated Press that the U.S. made clear it and its allies would not accept the results of an election so rife with fraud.

Prior to the votes being disqualified, preliminary results had put Karzai in the lead with about 54 per cent of the vote.

On Tuesday, Karzai accepted the panel's fraud findings and endorsed the runoff election.

Karzai will face off against his main opponent, Abdullah Abdullah, the country's one-time foreign minister.

"I expected the run-off based on the votes and that was the expectation of the people of Afghanistan," Abdullah said.

U.S. President Barack Obama released a statement praising Karzai's decision to accept a runoff as a key step in establishing "a credible process" for the Afghan people.

Prime Minister Stephen Harper called Karzai's decision on a runoff vote "an important step in the country's ongoing transition to democracy" in a statement.

Election challenges

A second vote will come with challenges, including problems with security, winter weather and the logistical issues involved with pulling off an election in just two weeks.

UN Secretary-General Ban Ki-moon said it would be a "huge challenge" to have a runoff vote without the widespread fraud of the first Aug. 20 election.

Earlier Tuesday, the former Canadian ambassador to Afghanistan told CTV's Canada AM that a second vote would give Afghans the chance to see a "legitimate result."

"The opportunity for Afghans to vote again restores the prospect of a legitimate result, which is what everyone wants," Christopher Alexander said during an interview in Toronto.

But the former ambassador said Abdullah will have a difficult job taking over Karzai's place in the polls if another vote does take place.

"Let's be realistic: He came a fairly distant second and he'll have to run a very good campaign if he's going to make up that ground," he said.

With files from The Associated Press