The US special envoy to Afghanistan, Richard Holbrooke, had a heated row with the Afghan president, Hamid Karzai, in the aftermath of the election, according to reports. Sources described the meeting as "a dramatic bust up" and "explosive", according to the BBC.
Holbrooke is said to have challenged Karzai over allegations of ballot-stuffing and fraud and suggested that a run-off to decide the next president – which would be held if no candidate obtained more than 50% of the votes – would boost the credibility of the democratic process.
Karzai reportedly reacted angrily to Holbrooke's criticisms, which also focused on deals struck by the incumbent president with warlords in a bid to garner support before the election. The tense meeting, held on the day after the poll, was said to have been noticeably briefer than a discussion Holbrooke held with Karzai's main rival for president, Abdullah Abdullah.
Abdullah and international observers have been critical of the conduct of the vote. Britain's ambassador, Mark Sedwill, said on Wednesday that the authorities were investigating 200 allegations of electoral fraud, 35 to 40 of which could be "material to the outcome" if upheld.
With 17% of the votes counted, Karzai had 45% of the votes compared with Abdullah's 35%, according to the official election commission. The final election result is not expected until 17 September, with a preliminary result expected between 3 and 7 September.
A spokesman for the US embassy in Kabul rejected reports that there had been shouting, or that Holbrooke had stormed out of the meeting. A spokesman for the presidential palace also denied that there had been a row.
Relations between the US and Afghanistan have been strained since Barack Obama entered the White House. Senior figures in Washington have criticised the alleged incompetence and corruption of Karzai's administration, while Karzai has hit back by insisting he is not a puppet of the international community.
US plans to push for a western-style chief executive to work under the president are seen as reflecting a lack of faith in the ability of whoever wins the election to curb corruption and extend the influence of the Kabul government in the face of Taliban advances.