President Hamid Karzai nudged closer to the 50 percent threshold needed to avoid a runoff in Afghanistan's election, according to the latest results released Sunday.

The Aug. 20 ballot has been marred by accusations of vote-rigging and election officials said they threw out results from 447 out of more than 26,000 polling sites because of fraud allegations. The head of the Independent Election Commission, Daoud Ali Najafi, said it was not yet clear how many votes were affected.

With 74 percent of polling stations counted, Karzai is leading with 48.6 percent. Top challenger Abdullah Abdullah has 30.1 percent. Karzai needs more than 50 percent to avoid a second round against Abdullah.

The country's election commission has slowly been releasing partial results, but says it will complete the count from all polling stations later this week.

Those results won't be finalized until later this month, after a complaints commission investigates more than 650 claims of serious violations on voting day and after. These include charges by Abdullah that Karzai supporters stuffed ballot boxes with tens of thousands of votes.

The commission has the power to nullify the results from districts or provinces, or even call for a new election, if it finds large-scale fraud.

Former Foreign Minister Abdullah on Saturday urged the election commission to stop announcing preliminary results because of "highly suspicious numbers" in tallies released so far.

He said a number of polling stations posted nearly identical numbers for Karzai and none for any other candidate. The challenger alleged electoral officials were beholden to Karzai, who appointed them.

"It is state-engineered fraud. It is not violations here and there," Abdullah said.

Commission chairman Najafi insisted Sunday that the commission was unbiased.

"The Independent Election Commission has been completely impartial in fulfilling its duties throughout the process," he said.

International and Afghan observers have been critical of the vote but have withheld judgment until counting and fraud investigations are complete.