KABUL, Afghanistan (CNN) -- Incumbent President Hamid Karzai's chief rival, Abdullah Abdullah, repeated his charges of widespread ballot fraud Monday and declared that Karzai "single-handedly put Afghanistan at risk by trying to rig the elections."
Election workers unload ballot boxes Sunday at the Independent Election Commission headquarters in Kabul.
As Afghanistan's elections commission prepared to release preliminary voting results in the nation's presidential race on Tuesday, Abdullah told CNN in an interview that his campaign had received what he described as credible reports of fraud in the southern provinces, where security was poor and turnout less than 10 percent.
Abdullah said ballot boxes were stuffed with additional votes, with 90 percent of them going to Karzai.
"This is stealing the elections and it will not be accepted," Abdullah said in the interview. He said he based his allegations on accounts of witnesses and on videos, but no videos were made public nor was it clear whether any had been turned over to the organization investigating election complaints.
A spokesman for Karzai's presidential campaign, Waheed Omar, said the allegations were without merit.
"This is an all out propaganda war that is undermining the process of the ECC [the Electoral Complaint Commission] by bypassing the legal institutions and making it an all out media campaign," Omar said.
The ECC investigates complaints of voting irregularities and fraud. ECC officials said that as of Monday, they had received over 600 complaints from voters around the country, and officials characterized dozens as the highest priority for investigation.
Abdullah said he believed that the ECC would investigate charges of fraud in good faith but called on the international community to guarantee the credibility of the process, saying that if it failed "it will have consequences for Afghanistan, for all of us."
Abdullah specifically suggested that unanswered fraud in the elections could result in increased tension in the country. Asked whether he thought it would lead to violence at the hands of his supporters, he replied, "I'll try and prevent that, but all I can promise is that I will be with the people."
Abdullah brushed away any suggestion that he might make some sort of agreement with Karzai to join a new government led by the incumbent.
"I will not make a deal, enough deals have been made in this country and that's taking this country to the past," Abdullah said.
The charges and counter-charges from both campaigns come as the Independent Election Commission in Afghanistan is preparing to release partial results on Tuesday. The organization announced Monday in a briefing that it expected to release the results from 2,400 of 6,000 polling centers around the country at a press conference Tuesday. Watch how results will come piecemeal »