Partial results issued for last month's Afghan presidential election have given incumbent Hamid Karzai 54.1% of the vote, the first time he has been shown with enough votes to win in a single round.
The victor needs 50% plus one vote to avoid a second round run-off.
The results, announced by the Independent Election Commission with 91.6% of polling stations tallied, gave Mr Karzai's main rival Abdullah Abdullah 28.3% percent of the vote.
The commission said it had set aside results from 600 polling stations where it suspects irregularities.
Earlier, Afghanistan's mainly UN-appointed election watchdog said it has found 'clear and convincing evidence of fraud' in last month's presidential election.
The Electoral Complaints Commission has ordered a partial recount in light of the evidence.
Most of the stations where it found fraud had either a larger than expected number of votes cast or a higher than expected proportion cast for a single candidate in the 20 August poll.
The UN envoy to Afghanistan has called on the country's electoral officials to ensure results of fraud-clouded elections are clean and reflect the will of voters.
Kai Eide said any ballot boxes with evidence of irregularities should be excluded from the preliminary count.
'The integrity of these elections is of the utmost importance to Afghanistan and to its international partners,' Mr Eide said in a statement.
Separately, a suicide car bomber has detonated his explosives outside a NATO military base at the international airport in the Afghan capital, killing at least two civilians.
Ministry of Health official Farid Raeed said the injured - six in total - had been brought to two hospitals in Kabul.
A police official confirmed the blast but had no immediate information on casualties, while a private television channel said there were a number of casualties among Afghans and foreign troops.
NATO, which runs the military side of the airport, had no immediate comment.
The Taliban claimed responsibility for the blast and said the target had been foreign soldiers at the airport.
The airport that has seen a series of Taliban rocket attacks and a suicide strike in the past.
Afghan officials running the civil section of the airport said domestic and foreign flights were not interrupted by the attack, part of the latest spell of rising violence in Afghanistan in recent years.
The attack comes less than a month after a suicide car bomber detonated his explosives outside the sprawling NATO-led headquarters in Kabul, killing at least seven and wounding 100.