Final poll results are not expected until the end of September
Partial results from Afghanistan's presidential election show incumbent Hamid Karzai has extended his lead.
With three-quarters of votes counted, Mr Karzai had 48.6%, followed by Abdullah Abdullah with 31.7%.
Officials said results from 447 of about 28,000 polling stations had been annulled, after fraud investigations.
The winner needs to secure an outright majority of 50% to avoid a run-off. The 20 August poll has been marred by allegations of widespread fraud.
Meanwhile, the German Chancellor Angela Merkel and British Prime Minister Gordon Brown have called for an international conference on Afghanistan to be held before the end of the year.
The conference would help Afghanistan to "take more and more responsibilities" and make progress on security, good governance and development, the leaders said.
The BBC's David Loyn in Kabul says it looks likely that Mr Karzai will eventually pass the 50% threshold, given that much of the remaining votes to be announced are from his southern powerbase.
Vote held on 20 August for presidency and provincial councils
More than 400 insurgent attacks on polling day, Nato says
More than 2,000 fraud allegations, 600 deemed serious
Final result expected end of September
Candidate needs more than 50% to avoid runoff
Out of 4.3m valid votes, Mr Karzai had so far won 2.08m and Mr Abdullah 1.36m, said Independent Election Commission official Daud Ali Najafi at Sunday's news conference in Kabul.
Another presidential candidate, Ramazan Bashardost, was a distant third, with fewer than half a million ballots.
Results from some polling stations where 100% of votes went to Mr Karzai would be allowed to stand unless fraud was proved to have taken place, election officials added.
The partial results are provisional, pending investigations into allegations of fraud.
Final results are due on 17 September, but analysts say they are not now expected until the end of the month.
Allegations of fraud have been made against all the prime candidates and the election commission has been investigating more than 2,000 complaints of irregularities, more than 600 of them deemed serious.
Mr Abdullah, a former foreign minister, warned in a news conference on Saturday that "state-engineered fraud" could fuel instability and urged the international community to intervene.
There have been been fears that doubts over the poll's legitimacy could lead to unrest. Mr Abdullah's powerbase is in the north, among ethnic Tajiks, while Mr Karzai's heartland is in the Pashtun-dominated south.
Members of the US-led coalition in Afghanistan have stressed in recent days their long-term commitment to keeping troops in the country to fight a resurgent Taliban, despite concerns about fraud and low turnout in the elections.
But a Nato air strike on two hijacked fuel tankers in northern Kunduz province on Friday, which killed scores of people, including reportedly some civilians, has revived controversy over Western military operations in Afghanistan.
On Saturday, the commander of US and Nato troops in Afghanistan, Gen Stanley McChrystal, promised a full investigation into the air raid.