Afghan election officials have said all ballots from 571 polling centers in last month's parliamentary election have been disqualified by fraud.
Independent Election Commission (IEC) spokesman Nur Mohammad Nur said the votes for hundreds more sites were being audited.
It was not clear how many ballots were affected by the decision.
A total of 5,510 polling centers were reported open on election day.
Meanwhile, a spokesman for the Electoral Complaints Commission, Ahmad Zia Rafat, said a total of 4,674 complaints had been received from candidates and voters.
"The New York Times," citing Afghan and Western officials, reported that that nearly a quarter of the votes are likely to be thrown out because of fraud.
The IEC postponed the announcement of preliminary results, slated for October 17, until October 20 in order to have extra time to be "more accurate and precise."
compiled from agency reports