Former opposition leader Abdullah Abdullah led on Sunday after the first official results from Afghanistan's presidential election, but recorded incidents of serious fraud exceed figures for 2009, when over a million suspect votes were thrown out.

Initial results based on 10 percent of the vote from 26 out of 34 provinces showed Abdullah in the lead with 41.9 percent, the Independent Election Commission said, while Western-leaning academic Ashraf Ghani came second with 37.6 percent.

A third candidate, running with the backing of two of President Hamid Karzai's brothers, trailed far behind with 9.8 percent.

"I want to make clear that the results could change in future, as we announce the results with additional percentages of the vote and this is not the final result," said the chairman of the election commission, Ahmad Yousuf Nuristani.

Afghanistan's allies praised the April 5 vote as a success because of the high turnout, estimated at 60 percent of 12 million eligible votes, and the failure of Taliban militants to stage high-profile attacks on the day.

But evidence of widespread fraud could undermine the legitimacy of an election meant to usher in Afghanistan's first democratic transfer of power, as incumbent Hamid Karzai prepares to step down after more than 12 years in power, and as Western forces prepare to leave.

The election complaints body hinted it might need more time than expected to investigate all of the complaints though the volume would not affect the overall schedule for electing a leader. Final results are due on May 14.

"There is a possibility, in order to review the high number of complaints accurately, that we may expand the time frame for reviewing complaints in provinces for some days," said Nader Mohseni, spokesman for the Independent Election Complaints Commission (IECC).

The three front runners have all complained of fraud.

To win, a candidate must secure more than 50 percent of valid ballots. Failing that, the top two candidates go into a run-off. - Reuters