Abdullah Abdullah, Afghanistan President Hamid Karzai's top challenger in the presidential election, has agreed to a run-off vote. (Jerry Harmer/Associated Press)

Afghanistan's top election official must be removed before the country casts ballots in the Nov. 7 run-off vote, says presidential candidate Abdullah Abdullah.

Azizullah Lodin, chairman of Afghanistan's Independent Election Commission, has "no credibility" and must be replaced immediately, Abdullah said on Monday.

"We will wait for the commission's reply until Oct. 31 and until then we suspend all of our relations with the commission," Abdullah said.

Lodin has denied accusations he is biased in favour of incumbent President Hamid Karzai. The former foreign minister is Karzai's run-off contender in the presidential election.

The two candidates announced on Sunday there would be no power-sharing deal between them ahead of the Nov. 7 vote.

Abdullah held a press conference in Kabul on Monday and laid out a list of "minimum conditions" for holding a fair second round of voting.

Abdullah said any election workers implicated in fraud from the first round of voting should be removed. More than 200 election workers have already been removed from their jobs ahead of the run-off vote, according to reports.

Abdullah also called for the suspension of several ministers he said campaigned for Karzai ahead of the campaign period.

The Aug. 20 first-round vote was marred by widespread fraud. After ballots from thousands of polling stations were invalidated by a UN-backed election commission, Karzai's tally fell below the 50 per cent threshold needed for victory, sending the country into the run-off vote.

Abdullah campaign officials have previously accused the top three members of Afghanistan's Independent Election Commission of bias, saying they should be replaced to ensure the next vote is fair. The commission has so far rejected the calls.

With files from The Associated Press