Former foreign minister Abdullah Abdullah leads the race to become Afghanistan's next president, according to the latest official tally of votes released on Sunday, but is short of an outright majority.

Afghanistan's Independent Election Commission said initial results based on almost 50 percent of the vote from the 34 provinces showed Abdullah in the lead with 44.4 percent, followed by Western-leaning academic Ashraf Ghani with 33.2 percent. A win of less than 50 percent would mean the election goes to a second round.

Zalmay Rassoul, backed by two of President Hamid Karzai's brothers, trailed far behind with 10.4 percent.

Afghanistan's allies hailed the April 5 vote a success because of the high turnout, and the failure of Taliban militants to stage any big attacks on polling day. But evidence has subsequently emerged of widespread 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. Final results are due on May 14, and a run-off, if needed will take place in late May.