Afghan President Hamid Karzai's main challenger said on Sunday he had evidence last week's election had been widely rigged by the incumbent and that he had lodged more than 100 complaints.
Counting is underway following Thursday's vote to choose a new president and 420 councillors across 34 provinces, but official preliminary results are not expected until at least Tuesday.
Former Foreign Minister Abdullah Abdullah, whom polls gave a fighting chance of pushing the election to a second round, said he had evidence of widespread rigging. Abdullah and Karzai's camp both say they are ahead in the vote count.
"The initial reports we are receiving are a bit alarming, I must say," he said. "There might have been thousands of violations throughout the country, no doubt about it."
Abdullah accused Karzai of "widespread rigging" and said his team had lodged more than 100 complaints with election officials.
"This has to be prevented. That's critical for the survival of the process and that's critical as far as the hope for a better life of the Afghan people is concerned," Abdullah said.
In a separate news briefing, the country's election watchdog said it was dealing with scores of complaints, but there was no sign they would directly affect the result.
The Independent Election Commission also said partial results would be released on Tuesday, and repeated its warning to candidates that they should not make premature declarations.
"Vote complaints"
Two opinion polls ahead of the election predicted Karzai would win, but not by enough to prevent a second round run-off against Abdullah in October. Karzai must win more than 50 percent of the vote to avoid a runoff.
The Election Complaints Commission (ECC) said it had received 225 complaints of which 35 had been labelled a priority.
"The allegations contained in the complaints we have received so far range from voter intimidation, violence, ballot box tampering (to) interference by some IEC (Independent Election Commission) officials," ECC chairman Grant Kippen told a news conference.
Kippen said the ECC was aware of "significant complaints" of vote irregularities, but that there were no specific charges against individual candidates such as Karzai.
Abdullah said the southern provinces of Ghazni and Kandahar were major areas of concern. He said vastly exaggerated voter turnouts were being reported, as well as ballot box stuffing well after the actual vote.
With the outcome still unpublished and both sides claiming victory, Washington's envoy to the region, Richard Holbrooke, said Karzai and Abdullah had both promised to respect the result.
"So the United States' position, and that of all our NATO allies, is unanimous: we all will respect the decision of the Independent Election Commission," he said on a visit to the western province of Herat on Sunday.
Since voters in the south were expected to back Karzai, poor turnout there increases the chance of a run-off.