Ahmad Yusuf Nuristani said that an estimated 3.5 million people had voted by midday (0830 GMT), five hours after polls opened, 64 percent of them men and 36 per cent women.
"This figure may have increased to more than seven million by 5:00 pm," he told a news conference. Polls officially closed at 5:00 pm.
Around 13.5 million people were eligible to vote, putting the estimated turnout above 50 percent -- a significant increase on 2009 when only around a third of voters cast ballots.