President Hamid Karzai and top challenger Abdullah Abdullah both have roughly 40% of the nationwide vote for president with 10% of polling stations counted, the Afghan election commission said yesterday.
If neither Mr Karzai nor Mr Abdullah gets more than 50% of the vote the two will face each other in a run-off, likely in early October.
The Independent Election Commission plans to release more results in the coming days but final certified results of last week's election won't be ready until at least mid-September.
Low voter turnout and allegations of fraud have cast a pall over the election.
Mr Abdullah has accused Mr Karzai of widespread vote rigging, including ballot stuffing and voter intimidation. Karzai's camp has levelled similar accusations.
Both campaigns have denied the claims.
The Independent Election Commission announced that Mr Karzai has 40.6% and Mr Abdullah has 38% of the votes in the country's first official returns since millions of Afghans voted for president last Thursday.
But the returns come from only 22 of the country's 34 provinces and represent votes from just 10% of the country's polling stations.
Of the roughly 525,000 valid votes counted so far, the majority came from Kabul, nearby Parwan and Nangarhar provinces, Kunduz and Jowzjan provinces in the north and Ghor province to the west.
In the volatile south, less than 2% of Kandahar votes have been counted, and no votes in Helmand have been tallied, the commission said.
Both Mr Karzai and Mr Abdullah have claimed they were leading in early returns, but no official figures have backed those assertions.
Meanwhile, six presidential candidates — none of them Mr Abdullah or Karzai — warned that fraud threatens to undermine the election and could stoke violence.
The six presidential candidates said in a statement that dozens of complaints filed could affect the outcome of the election “to the point that many are seriously questioning the legitimacy and credibility of the results”.
“Fraud in the elections could result in increased tension and violence,” the six added.
The signatories are all long-shot candidates. The most prominent is Ashraf Ghani, a Western-educated former finance minister who has been suggested as a “chief executive” under the next president tasked with handling day-to-day management of the government.
The election commission said it had fired four election workers in northern Balkh province for attempted fraud.