KABUL: President Hamid Karzai on Thursday flatly denied major fraud in Afghanistan's troubled elections and urged foreign allies not to interfere in probes over irregularities that could slash his clear lead.

Afghans went to the polls last month to elect a president for only the second time in history with a Taliban insurgency at its deadliest since the 2001 US-led invasion replaced the Islamist regime with Western-backed rule.

The Independent Election Commission (IEC), which has been accused of bias towards Karzai, has released results in an agonisingly slow process alongside mounting claims of massive vote-rigging in favour of the president.

On Wednesday, the final preliminary vote put Karzai on track to be reelected with 54.6 percent but recounts at more than 2,500 polling stations could yet tip the balance and force him into a run-off with his rival Abdullah Abdullah.

Addressing reporters publicly for the first time since the eve of the August 20 poll, Karzai played down allegations of fraud and said he would respect investigations by the IEC and UN-backed Electoral Complaints Commission.

"Media has reported major fraud. It wasn't that big. If there was fraud, it was small -- it happens all over the world," Karzai told a news conference at his heavily fortified palace in the Afghan capital.

But the president, whose nearly eight-year rule has been marred by worsening violence, corruption and cooling ties with the West, has been on a collision course with his international backers over the fraud-tainted election.

On Wednesday, observers from the European Union said they had identified 1.5 million votes that could be fraudulent -- nearly a quarter of the total valid votes and 1.1 of them cast for Karzai.

"If there is fraud, it has to be investigated, but investigated fairly and without prejudice," Karzai said Thursday.

"I hope our foreign friends respect the people of Afghanistan and let the IEC and the ECC fulfil their work without interference," he added.

Karzai's campaign office reacted furiously to the EU observers, accusing them of meddling and damning the announcement as "partial, irresponsible and in contradiction with Afghanistan's constitution."

Abdullah trails with 27.8 percent of the preliminary count, but the final result of will likely not be known until all fraud allegations are resolved, which could take weeks.

Afghanistan is gripped by the deadliest violence and an expanding Taliban insurgency that has made parts of the north and west increasingly volatile, on top of the south and southeast where the Islamist militia are strong.

Threats of militant violence are believed to be behind the meagre election turnout of 38.7 percent, compared to the 70 percent turnout among voters who registered in the first presidential election in 2004.

On Thursday, an attack on an Italian military convoy from the NATO-led force killed at least three people in the Afghan capital, witnesses said.

President Barack Obama warned Wednesday he would make no "immediate" decision on troops for Afghanistan, despite the top US military officer saying extra soldiers would probably be needed on top of a 62,000-strong force.

As more and more Americans sour towards the eight-year war, Obama aides presented lawmakers with a set of proposed benchmarks to measure progress.

Under the objective of promoting a more capable government, one benchmark cites Afghanistan's "ability to hold credible elections in 2009 and 2010."

"Well, guess what -- that one is not going to get a glowing rating," said an official on condition of anonymity.

The IEC says recounting is under way, but has given no timescale for the process. A leading think tank called for an interim government as the only way to lead the destitute and war-torn country out of a political quagmire.

The International Council on Security and Development (ICOS) warned that delays could create a dangerous political vacuum and recounts could take Karzai below the threshold needed to avoid a run-off.

"The protracted electoral fraud investigation means that it will not be possible to hold a run-off before November," the London-based group said.

But by then, the harsh winter could potentially delay any vote until May, leaving Afghanistan in a constitutional vacuum for eight months," said ICOS.

"An interim government is the only option left to lead Afghanistan out of the political quagmire," said ICOS policy analyst Alexander Jackson.