Afghan election officials racing to meet a narrowing window for a possible presidential runoff said Friday they will recount a sample of 10 percent of suspect ballot boxes to speed long-delayed results of the disputed election.

Preliminary results from the Aug. 20 vote show President Hamid Karzai winning outright with 54.6 percent. But the election has been mired in allegations of ballot stuffing and voter coercion. If enough votes are found to be fraudulent, Karzai could dip below the 50 percent threshold needed to avoid a runoff with chief challenger Abdullah Abdullah.

The reasonable timeframe for any runoff has narrowed to the last two weeks in October, before winter snows make much of the north impassable, election officials have said. Missing that window could delay any runoff until spring, creating a power vacuum in a country already struggling to fend of the resurgent Taliban and losing support from international allies.

The Afghan election commission and a U.N.-backed panel investigating widespread fraud allegations agreed to audit and recount ballots from 313 of the 3,063 polling stations deemed suspicious, said Grant Kippen, the Canadian head of the U.N.-supported panel.

"It will be fair," Kippen said. "We've got these international experts who have been doing this and who have advised that this is a good approach." He said the margin of error is less than 1 percentage point.

The panel — which is the final arbiter of the vote result — had previously ordered Afghan officials to audit and recount all 3,063 polling stations whose results were suspect because of tallies with more than 100 percent turnout or nearly all votes cast for one candidate. But worries that such a vast recount could take months prompted the decision to count a sample instead.

The 313 ballot boxes were randomly selected in front of candidate agents and observers, said Nellika Little, a spokeswoman for the U.N.-supported Electoral Complaints Commission.

The selected ballot boxes will be retrieved from the provinces as soon as Saturday, said Zekria Barakzai, the deputy chief electoral officer of the Afghan election commission.

Afghan election officials and the complaints commission issued a joint statement confirming the agreement but retracted it less than two hours later, saying that the wording had not been finalized. A spokeswoman said the essentials of the agreement still held.