KABUL - More results were expected to trickle out of Afghanistan's election counting house on Wednesday as officials raised the death toll from a truck bombing that highlighted the problems the eventual winner will face.

Authorities in Kandahar, Afghanistan's second biggest city and the spiritual home of the Taliban, raised the toll from Tuesday night's truck bomb to 43 dead and 65 wounded, all civilians.

The attack was the worst of its kind in over a year and came the same day four American servicemen were killed, making 2009 the deadliest year for foreign forces since the overthrow of the Taliban in 2001 in the wake of the September 11. attacks on the U.S.

The Kandahar bomb also shattered a relative lull in violence since last Thursday's election and the start of the Muslim fasting month of Ramadan at the weekend.

The first tranche of results released on Tuesday showed incumbent President Hamid Karzai with 41 percent and his main challenger, Abdullah Abdullah, with 39 percent in a race that will go to a second round unless either gets more than 50 percent.

Around 30 minor candidates account for the remainder of the vote, but their supporters could be decisive in a run-off.

Major test

The elections are a major test for Karzai after eight years in power and also 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.

Election officials warned against drawing conclusions about the final count from the initial samples. They have promised to provide daily updates but the complete count is not due until September 3.

The results suggest a disappointing turnout of only around 5 million votes in a country of some 30 million people and an estimated 15 million eligible voters.

Taliban fighters had launched attacks and threatened reprisals against voters during the election, scaring many Afghans away from the polls, especially in the violent south.

Extra troops

More than 30,000 extra U.S. troops arrived in Afghanistan this year, most part of a package of reinforcements ordered by Obama in May in response to a growing Taliban insurgency.

More than 100,000 Western troops are now in the country, 63,000 of them Americans.

The number of foreign troops killed in Afghanistan this year now stands at 295, according to icasualties.org, a website which compiles official figures. Last year, 294 died.

The U.S. reinforcements sent by Obama, along with a British contingent already deployed in the south, have advanced deep into formerly Taliban-held territory, taking heavy casualties mainly from roadside bombs. More Western troops have died since March than in the entire period from 2001-2004.