Afghan officials said on Thursday they had delayed releasing further results from the nation's disputed presidential poll, adding further confusion to a contest which appears headed for a second round.
Votes from about 17 percent of 27,000 polling stations have been counted so far, meaning results could swing wildly in the coming days. Preliminary final results are due on September 3, with the final tally about two weeks later.
Afghanistan has been in political limbo since the August 20 vote, with partial results released so far showing President Hamid Karzai leading his main rival, former foreign minister Abdullah Abdullah, by about 43 percent to 34 percent.
Afghanistan's Independent Election Commission (IEC) said only votes from provincial council elections, held concurrently with the presidential poll a week ago, would be counted on Thursday.
Adding to an already chaotic picture, computer software failures meant counting was going slower than expected, said IEC deputy head Zekria Barakzai.
The election is a major test for Karzai after eight years in power and for U.S. President Barack Obama, who has poured in thousands of extra troops as part of his new regional strategy to defeat the Taliban and stabilize Afghanistan.
The picture will not become any clearer for at least two days, with no counting planned for Friday, a Muslim holiday.
"We will come up with new figures and information on Saturday," Barakzai told Reuters.
To avoid a potentially destabilising second round run-off in October, a candidate must win more than 50 percent of the vote.
The most likely outcome that can be gleaned from the partial election results released so far is that a run-off is likely, election observers say.
Foreign troop deaths hit 300
Security in Afghanistan has deteriorated rapidly this year, with attacks reaching their worst levels since the austere Islamist Taliban were ousted by U.S.-led Afghan forces in 2001.
Violence spiked further in the weeks leading up to the poll, which the Taliban vowed to disrupt, testing Obama's new strategy and softening support for the war in the United States, but the election went ahead with relatively few attacks.
However, at least 43 people were killed in a huge truck bomb blast on Tuesday in southern Kandahar city, the worst incident of its kind in more than a year. The Taliban denied responsibility for the blast.
With civilian and military casualties at record levels, 2009 has become the deadliest year of the war for foreign troops.
Three hundred have been killed so far this year compared with 294 in 2008, the previous worst year of the war.
Another five members of the NATO-led International Security Assistance Force (ISAF) had been killed in separate incidents over the past three days, ISAF and the U.S. military said.
ISAF said in a statement 12 Taliban fighters had been killed during a raid, backed by attack helicopters, on a clinic in southeastern Paktika province on Wednesday during which a Taliban commander was detained.
The Taliban commander, known as Mullah Muslim, was being treated for wounds suffered in a gunbattle with Afghan forces on election day, it said. One ISAF soldier was killed during the raid, the statement said.
Two U.S. service members were killed on Wednesday, one in the east and the other in the violent south, home of the Taliban-led insurgency. One was killed by a roadside bomb, the deadliest weapon used by insurgents, and the other in a gunbattle, ISAF said in a separate statement.
Another U.S. soldier was killed during a firefight with insurgents after a patrol was hit by a roadside bomb in the south earlier on Thursday, ISAF said.
Another ISAF service member whose nationality was not released died on Tuesday of wounds suffered in a roadside bomb blast almost two weeks ago.
More than 30,000 extra U.S. troops have landed in Afghanistan this year, most part of a package of reinforcements ordered by Obama in May. More than 100,000 Western troops are now in the country, 63,000 of them Americans.