The head of the Independent Election Commission Daoud Ali Najafi couldn't say how many votes are affected.
The latest election results show President Hamid Karzai creeping closer to the important 50 percent threshold with 48.6 percent. Top challenger Abdullah Abdullah has 30.7 percent. The count is based on results from 74 percent of the country's polling stations.
The country's election commission has slowly been releasing results from the Aug. 20 vote. But hundreds of allegations of fraud have slowed the work.
Results won't be finalized until later this month after fraud allegations are investigated.
The election commission has so far published only partial results of the Aug. 20 vote, and says it has excluded ballots where it suspects fraud.
Yet results on its web site already include a remarkable number of figures that end in zeros.
Karzai's main opponent Abdullah Abdullah says this is proof of fraud on a massive scale.
At a news conference on Saturday, Abdullah's aides passed out lists of more than 100 polling centers where they said a check of the official results online would show numbers that are obviously bogus.
"Here in these links you see that one hundred percent of the vote has gone to one candidate, and that candidate is famous enough - I don't think you would like me to name him but if you do, it is Mr. Karzai, yeah," said Karzai's main rival, Dr. Abdullah Abdullah. He displayed the polling station result that reflected votes only for President Karzai but zero for any other candidate.
"I request the election commission not to announce the provisional result any more because it is fraudulent and some of these accounts require investigation. It is not just a violation; it is more than a violation by the IEC member in those polling stations."
At one polling station in a school in the Zerok district of Paktika province, exactly 400 votes were cast, all for Karzai. At a mosque in Kandahar's Sayed Bosa village, Karzai received all 4,085 votes cast. Of the mosque's eight polling stations, two reported Karzai with exactly 500 votes, two with 510, three with 520 and one with 515.
These and other round numbers pop out of tables published on the election commission's Web site.
Allegations of fraud have delayed official results from the election, now more than two weeks old, and threaten to wreck confidence in a vote that had been a centerpiece of U.S. President Barack Obama's regional strategy.
"We have insecurity in this county, we have bad government we have corruption we have narcotic, we have a war, we have insurgency. On top of that if a leadership is imposed upon the people based on fraudulent election, what will happen?" Abdullah told the Kabul news conference, saying such circumstances are "a recipe for instability."
IEC spokesman Noor Mohammad Noor said the election commission stood by the numbers on its web site and referred complaints to a separate Electoral Complaints Commission, known as the ECC.
Karzai's staff were not available for comment.
The partial results so far show Karzai leading but falling just short the outright majority (50% plus one) needed to win in a single round of voting.
Most of the ballots have yet to be counted in the south, the heartland of Karzai's support base and also the part of the country where Abdullah says most fraud took place.
The remaining southern results could swing the election for Karzai in a single round, but Abdullah says he will reject the outcome if fraudulent results are not excluded.
Western officials say fraud can still be corrected by the complaint commission, which is led by a Canadian and has the authority to set aside ballots it suspects were stuffed. The watchdog says it is probing more than 2,000 complaints, including more than 600 serious enough to affect the results.