Washington  - The United States Tuesday urged Afghans to exercise patience and restraint as ballots cast in the country's presidential election last week continue to be counted amid allegations of fraud.

Afghanistan's election commission released a partial result on Tuesday showing President Hamid Karzai narrowly leading over his chief rival, former foreign minister Abdullah Abdullah, by a 40.6-to- 38.7-per-cent margin.

But that represents only 10 per cent of the ballots cast on Thursday. A final outcome is not expected to be announced until at least mid-September.

"We all need to be patient, allow the respective authorities to do their jobs thoroughly, and we have to wait for the results to be released," State Department spokesman Ian Kelly said.

"We call on all parties to refrain from speculation until the national results are announced," he said.

A candidate must win 50 per cent of the vote to avoid a run-off, which would take place in October.

Afghanistan is conducting its first independently run election in decades, but it has already been plagued with complaints and allegations of corruption. The country has set up a commission to review and potentially investigate complains.

Abdullah held a press conference on Tuesday to declare that fraud was "widespread" and accuse Karzai of playing a role in rigging the vote. (dpa)