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.
With counting underway following Thursday's vote, the country is on tenterhooks before an official result, although the start of the Muslim fasting month of Ramadan and a relative lull in violence has helped calm tensions.
An election result respected by the candidates and their supporters is crucial for the country and for U.S. President Barack Obama, who has made stabilising Afghanistan his top foreign policy priority.
Washington has poured thousands more troops into Afghanistan this year as part of Obama's new regional strategy to defeat the Taliban, but polls show support for the 8-year-old war is slipping as casualties increase from the growing insurgency.
