International pressure to resolve Afghanistan's disputed election intensified on Saturday when senior foreign officials talked with President Hamid Karzai, Reuters reported.

The discussions, some by telephone and some in person, took place just before the U.N.-backed Electoral Complaints Commission was to announce the findings of its investigation into allegations of fraud in the Aug. 20 presidential vote.

The accusations have left Afghanistan in a state of political uncertainty at a time when U.S. President Barack Obama is deciding on sending more troops to fight the Taliban.

If Karzai's vote tally is reduced, he could face a run-off round against former Foreign Minister Abdullah Abdullah.

"The second round is definitely on the radar screen right now," said a Western official close to the process. "This is why there are delays. There are some tense negotiations going on."

A host of high-level visitors arrived in Kabul for talks before the announcement, including U.S. Senator John Kerry, who is chairman of the U.S. Senate Foreign Relations Committee, and French Foreign Minister Bernard Kouchner.

"This is very complicated," Kouchner told reporters. "We want to understand why it is not possible to get a consensus. But you need to work together."

Zalmay Khalilzad, the former U.S. ambassador to Afghanistan, was also in Kabul on a private visit, the U.S. embassy said.

Karzai separately spoke by phone to British Prime Minister Gordon Brown, U.N. Secretary General Ban Ki-Moon, Pakistan President Asif Ali Zardari and U.S. Secretary of State Hillary Clinton, Karzai's office said.

A U.S. diplomat said Kerry's goal was to "highlight the need for a legitimate outcome in this election".

The elections are a vital element in Western plans to stabilize Afghanistan and deny sanctuary there to militants believed to have used it as a base for actions across the globe, including the Sept. 11, 2001, attacks on the United States.

More than 100,000 foreign troops are in Afghanistan fighting Taliban insurgents but growing casualties and doubts about the Karzai government are undermining support for the effort in the United States, Britain and other countries involved.