Charges of fraud in Afghanistan's presidential election are extensive enough that they could sway the final result, the commission investigating the complaints said Sunday. The independent Electoral Complaints Commission has received 225 complaints since polls opened Thursday, including 35 allegations that are “material to the election results,” said Grant Kippen, the head of the UN-backed body. The figures include complaints about both the presidential balloting and provincial council polls. Millions of Afghans voted in the country's second-ever direct presidential election, although Taleban threats and attacks appeared to hold down the turnout, especially in the south. President Hamid Karzai's top challenger, former foreign minister Abdullah Abdullah, accused the president of rigging the vote in an interview Saturday. Another presidential candidate has displayed mangled ballots that he said were cast for him and then thrown out by election workers. Election observers have said the voting process was mostly credible, but are cataloging instances of fraud and violence. The most common complaint in the 35 high-priority allegations was ballot box tampering, Kippen said. He stressed that the number was likely to grow. The commission has only received complaints filed at provincial capitals and Kabul so far and is still waiting for complaints that were filed at polling sites. The top Afghan monitoring group has said there were widespread problems with supposedly independent election officials at polling stations trying to influence the way people voted. That group, the Free and Fair Elections Foundation of Afghanistan, also catalogued violations such as people using multiple voter cards so they could vote more than once, and underage voting. The US special envoy to Afghanistan said allegations of vote rigging and fraud are to be expected, but observers should wait for the official complaints process to run its course before judging the vote's legitimacy. “We have disputed elections in the United States. There may be some questions here. That wouldn't surprise me at all. I expect it,” Richard Holbrooke told AP Television News in the western city of Herat. “But let's not get out ahead of the situation.” Holbrooke said the US government would wait for rulings from Afghanistan's monitoring bodies – the Independent Election Commission and the Electoral Complaints Commission – before trying to judge the legitimacy of the vote. The first preliminary results will not be released until Tuesday, and final certified results won't come until next month. If neither Karzai nor Abdullah gets 50 percent of the vote among a field of some three dozen candidates, then they will go to a runoff, probably in October.