Almost a quarter of the 5.6m votes cast in Afghanistan's parliamentary election last month were invalid, according to election commission officials.
Afghanistan's Independent Election Commission said it had ruled 1.3m votes invalid.
It also said that ballots collected from 2,543 of the 17,744 polling stations, which opened for the 18 September vote, had been disqualified.
The election went ahead despite a threat by the Taliban to disrupt the poll.
Western nations have been wary of describing the election as a success after a fraud-marred presidential election last year.
More than 4,000 formal complaints have been lodged with the UN-backed Electoral Complaints Commission, meaning it may be some weeks before final results are released.
