Interim leader Hamid Karzai (search) has won a majority of estimated votes cast in Afghanistan's landmark presidential elections, according to preliminary results released Sunday.

However, Karzai has not been declared the winner. An expert panel is still reviewing allegations of electoral fraud leveled by other candidates, and it may take another week for the announcement of official results.

Karzai has won 4,105,122 votes, more than half of the estimated 8,114,071 valid votes cast in the Oct. 9 vote. He must get more than 50 percent to win the election outright and avoid a runoff against his closest challenger.

Some 7,473,059 valid votes have been counted so far, with Karzai currently at 54.9 percent, 38.5 points ahead of his nearest rival, Yunus Qanooni (search).

It is possible that more votes were actually cast than the current estimate, but barring a near-reversal in the current pattern of results, the changes would not be enough to drop Karzai under the 50 percent mark. Electoral officials have said they will not call the election until the investigation into the fraud allegations and the vote count are both complete.

Karzai has served as the country's interim leader since U.S. forces drove out the former ruling Taliban regime in late 2001 for harboring Usama bin Laden (search).

Although many Afghans are frustrated at the slow pace of their country's recovery, Karzai is trusted as a bridge to foreign backers and has rounded up strong support in the cities and among fellow Pashtuns, the country's largest ethnic group.

Still, rivals have scored strongly among ethnic minorities in the north and center of the country, perpetuating the deep ethnic and factional divides that sustained years of fighting.

U.N. spokesman Manoel de Almeida e Silva said the panel met with election observers and some candidates' representatives on Saturday. It decided to recommend further investigation of less than 15 of some 100 ballot boxes quarantined.

Polling day passed without major violence, prompting American commanders and Afghan politicians to write off the Taliban as a fading force.

But the euphoria surrounding the elections received a damper on Saturday when a suicide attacker detonated grenades in a busy shopping street in Kabul, killing an American woman and an Afghan girl and injuring three Icelandic peacekeepers.

A purported spokesman for the Taliban claimed it carried out the attack, and said more suicide missions were being prepared.

Karzai condemned the attack as the work of the enemies of Afghanistan and Islam.

"The efforts of terrorists will be fruitless because the Afghan people are determined to continue on the path of reconstruction, democracy and stability," he said in a statement.