KABUL, September 1, 2009 (AFP) - The credibility of Afghanistan's elections could depend on a small team working day and night inside two heavily guarded peach villas in a wealthy Kabul suburb.

Afghanistan's independent Electoral Complaints Commission (ECC) has the arduous job of investigating more than 2,500 claims that fraud compromised the country's presidential and provincial elections on August 20.

Staff work seven days a week with the mostly Afghan workers exhausted by the dawn-to-dusk Muslim fast of Ramadan as they sit behind laptops at new desks on fitted carpets, probing the multitude of alleged irregularities.

As complaints pour in, filing cabinets are brought out of storage, neatly labelled and filled to bursting with documents.

"We have received 2,564 total complaints during the campaign period and 2,097 complaints on election day," said spokesman Ahmad Muslim Khuram as marksmen prowled the roof -- a sign that danger is real in Afghanistan.

Dressed in jeans, the young man talks about his past as presenter of an Afghan TV music show and the challenges of returning from a lifetime in exile after the 2001 US-led invasion overthrew the Taliban.

The ECC says the outcome of investigations into 690 complaints could determine who gets the presidency if the commission invokes its power to disqualify ballots, order a re-count or re-polling.

This year's most serious complaints, such as alleged ballot stuffing, voter intimidation and ghost polling stations, are more than double the number of "priority A" complaints received after Afghanistan's 2005 elections.

"I'd say it's one of the most difficult ones I've done because we've got 300 people working to make sure that we do the best job possible," said ECC chairman Grant Kippen, a Canadian who has worked on elections around the world.

So great is the workload that Kippen leaves open the prospect of pushing back the tight deadline to finalise investigations and certify the final result.

"There is a notional working date right now of September 17, but that is a working date only. If we find that we need more time, then we'll take what time is necessary," he told AFP.

It has already been a race against time. The commission only moved into its premises in May. Some of its provincial offices were not up and running until candidates were already pressing the flesh on the campaign trail.

"It's been really, really challenging," Kippen said.

With results from nearly half the polling stations announced so far, Karzai leads former foreign minister Abdullah Abdullah by 45.8 percent to 33.2 percent but still lacks the majority needed to avoid a second round.

Fraud is threatening to become a byword for the polls as Western allies have expressed dismay over charges of wrongdoing while Karzai and Abdullah each claim victory.

The contested nature of the election makes the ECC's work vital.

Operating on a budget of $13-million , the commission was set up with UN assistance as an independent Afghan entity under Afghan electoral law.

Its board is made up of two Afghan commissioners -- appointed by the Afghanistan Independent Human Rights Commission and the supreme court -- and three foreigners appointed by the UN special envoy to the country.

The team assigned to allegations from Kabul work in the basement. Nine investigators, lawyers and administrators sit in silence behind laptops on uncluttered desks.

While supposed to lend transparency to voting, the ECC has been criticised as "irrelevant" by analysts who accuse Karzai of cooking back-room deals to shore up as wide as possible a coalition after a first round victory.

Abdullah has alleged "state-engineered" fraud and says it "remains to be seen" if the ECC was strong enough to disallow suspect votes.

Others must determine whether the credibility of the elections is at risk, says the ECC, reserving judgement on how far -- if at all -- its findings could sway the final result.

"There are going to be people that don't like the decisions that we take but the hours that we're putting in (are) to make sure that we base whatever decisions we make on fact, on evidence," said Kippen.

Whenever that happens, the ECC will cease to exist 30 days after the results are finally certified.