Kabul ? President Hamid Karzai’s leading challenger accused him of using the Afghan state to “rig” this week’s election and detailed allegations of cheating by government officials in an interview Saturday with The Associated Press.

Abdullah Abdullah, once Karzai’s foreign minister, said he was in contact with other campaigns to explore the possibility of a coalition candidacy in case none of the 36 candidates won enough votes in last Thursday’s ballot to avoid a runoff, probably in October.

The accusations, which Karzai’s spokesman denied, are the most direct Abdullah has made against the incumbent in a contest that likely has weeks to go before a winner is proclaimed. Both Abdullah and Karzai claim they are in the lead based on reports from campaign pollwatchers monitoring the count.

Officials of Abdullah’s campaign have alleged fraud in several southern provinces where the insurgency is strongest and Karzai had been expected to run strong.

“He uses the state apparatus in order to rig an election,” Abdullah said in the interview. “That is something which is not expected.”

Abdullah said it “doesn’t make the slightest difference” whether Karzai or his supporters ordered the alleged fraud.

“All this happens under his eyes and under his leadership,” Abdullah said.

If Abdullah supporters believe the election was stolen, it could lead to the type of street violence that marred Iran’s presidential election in June. Abdullah has called for calm and says grievances should be resolved through the country’s Electoral Complaints Commission.

Abdullah said during the interview that government officials in Kandahar and Ghazni provinces, including a provincial police chief and a No. 2 provincial election official, stuffed ballot boxes in Karzai’s favor in six districts. He also said his monitors were prevented from entering several voting sites.

Karzai’s campaign spokesman Waheed Omar dismissed Abdullah’s allegations and claimed the president’s camp had submitted reports of fraud allegedly committed by Abdullah’s followers to the election complaint commission.