KABUL, Afghanistan | Abdullah Abdullah, the leading challenger to Afghan President Hamid Karzai, accused his rival on Saturday of using his power to manipulate the war-torn country's second-ever presidential election.
Mr. Karzai's former foreign minister also said he was in contact with other campaigns about forming a coalition against the incumbent should he not get 50 percent of the votes needed to win outright, a scenario that appears likely. He would not specify with whom he spoke or any further details.
The country's biggest domestic election observer group said its members saw several cases of fraud and irregularities in Thursday's voting. Taliban militants, making good on their promise to punish voters, cut off the inked fingers of at least two people, the group said.
European election observers said the vote was generally fair but not entirely free because of the Taliban intimidation that kept the turnout low, especially in the south.
Both Mr. Abdullah and Mr. Karzai have claimed to lead the vote based on reports from voting monitors, but election officials say preliminary results will not be known until at least Tuesday, and final results two weeks later. A runoff probably would take place in early October.
Mr. Abdullah said Karzai supporters within the government were guilty of fraud in several Pashtun-dominated southern provinces. Mr. Karzai, an ethnic Pashtun, was expected to fare well across the region, though Taliban intimidation appears to have reduced voter turnout.
"He uses the state apparatus in order to rig an election," Mr. Abdullah told the Associated Press. "That is something which is not expected."
He added that it was irrelevant whether Mr. Karzai was directly responsible because it is "under his leadership that all these things are happening, and all those people which are responsible for this fraud in parts of the country are appointed by him."
Pro-Karzai government officials in Kandahar and Ghazni provinces, including a provincial police chief and a deputy provincial election official, stuffed ballot boxes in the president's favor in six districts, Mr. Abdullah said, while several monitors were barred from entering voting sites.
Karzai campaign spokesman Waheed Omar rejected the charges. He said his team had filed reports with the Electoral Complaints Commission detailing suspected fraud by Abdullah supporters.
Losing candidates often claim fraud to "try to justify their loss," he told the AP.
Analysts say the recriminations may be political maneuvering to build leverage in case the one side finds polling results to be unsatisfactory. This carries with it concerns of unrest along ethnic or regional lines if supporters feel cheated, a divide that spans the mostly Pashtun south and northern provinces where Mr. Abdullah derives much of his support from ethnic Tajiks.
Each candidate has called for calm and asked the complaints commission to resolve the issue.
Based on his campaign's vote count, Mr. Abdullah said, he thinks a second round of voting will be necessary.
"These are very preliminary results, but still it puts me in the lead," he said. "It's not claiming victory. I'm saying in these early days and early preliminary results, I'm very happy."
The support of other candidates, with whom Mr. Abdullah said he was already in contact "either directly or indirectly," would raise his chances of unseating Mr. Karzai in a runoff.
The remaining top candidates - maverick member of parliament Ramazan Bashardost and former Finance Minister Ashraf Ghani - have given no word on whether they would endorse Mr. Abdullah.
Although Taliban vows to disrupt the vote resulted in significantly less participation than in the 2004 election, millions of voters showed up at the polls Thursday. In the south, where militants are the strongest, turnout was particularly low.
Sporadic attacks across the country on voting day left 26 Afghan civilians and militants dead.
Taliban militants, who had warned people against voting, cut off the ink-stained fingers of two voters in Kandahar province, said Nader Nadery, head of the Free and Fair Election Foundation of Afghanistan, a monitoring group.
Among other irregularities, the group's observers noted that election officials in several areas were coercing people to vote for certain candidates; underage voters were casting ballots; and some voters turned up at the polls with boxes of voting cards to vote multiple times.
The National Democratic Institute, a U.S.-based group promoting democracy, said the vote "involved serious flaws." It further noted the absence of voter lists and a likely conflict of interest since the Independent Election Commission officials are appointed by Mr. Karzai.
Western officials had anticipated that elections would be far from perfect given the country's insecurity, hoping instead for a process that was acceptable. In Washington, President Obama said the vote was a move in the right direction.
Gen. Philippe Morillon, chief observer of a European Union's election mission, told Reuters news agency that the election had been "fair generally," but "free was not the case in some parts of the country due to the terror."
This article was reported with a grant from the Pulitzer Center on Crisis Reporting.