Afghans shout slogans during a protest to support presidential candidate Abdullah Abdullah (Reuters)

Afghanistan's presidential election result has been delayed for several days, as a dispute over alleged fraud threatens to derail the country's first democratic transfer of power.

Abdullah Abdullah, reported to be far behind in the vote count, welcomed the delay and called for an anti-fraud audit that could trigger a prolonged political stalemate as US-led combat troops end their 13-year war against the Taliban.

The United Nations and donor countries have been trying for months to prevent a contested election outcome, fearing a messy power struggle that could fuel ethnic unrest.

But with Abdullah and his poll rival Ashraf Ghani at loggerheads, many fear the deadlock could tip Afghanistan into street protests and uncertainty.

The Independent Election Commission (IEC) said on Tuesday (local time) preliminary results due out on Wednesday (local time) would be delayed as some ballot boxes from the June 14 run-off vote would be checked "to make sure of transparency".

"Now there is a time, there is a space, because of the delay," Abdullah told AFP in an interview at his heavily-fortified residence in Kabul.

"We are talking about measures that would be more robust, vigorous auditing (and) that would take care of the fraudulent ballot papers.

"Almost everybody now agrees there has been industrial-scale fraud... The outcome will not be considered legitimate if that is not being taken care of."

Abdullah, previously seen as the front-runner, boycotted the vote count over the alleged fraud, while his rival Ghani said the election was fair and claimed victory by more than one million votes.

Ghani's campaign team on Tuesday criticised the delay in results, but said it welcomed any attempt to reduce fraud.

"We believe the election commission should work in accordance to the election timeline and announce results on time," campaign spokeswoman Azita Rafat told AFP.

"If this delay is for the sake of transparency then we accept it, though it runs against the election law."

AFP