KABUL, Afghanistan (AP) An Afghan presidential hopeful said Tuesday that all indications are that nobody has won in the first round of voting over the weekend and a runoff must be held.

Zalmai Rassoul, a former foreign minister who is considered one of three front-runners in a field of eight candidates, also said that "massive fraud" took place in the balloting for a new leader. Hamid Karzai is constitutionally barred from a third term.

Saturday's election was largely hailed as a success after a high turnout and relatively little violence despite a Taliban threat to disrupt the vote. But there were reports of fraud, such as ballot-stuffing and government interference.

A spokesman for the election complaints commission said more than 3,000 complaints were received but only half of those were formally submitted. The others were largely telephone calls. "I can say that fraud and violations have taken place," said Nadir Mohsini.

Many have predicted that nobody would get the majority needed to win outright and a second round would need to be held. But Rassoul was the first front-runner to say it directly. His main rivals, Abdullah Abdullah, who was Karzai's main rival in the last presidential election in 2009, and Ashraf Ghani Ahmadzai, an academic and former World Bank official, have expressed confidence they could win in the first round.

"The data indicates that elections will go to the runoff round," Rassoul's campaign office said in an email, adding that his campaign offices had been instructed to prepare for a second round. He also claimed that "some candidates and their supporters have committed extensive fraud," although he gave no specifics in the statement.

Some candidate forecasts and partial results are expected in the coming days. Noor Mohammad Noor, a spokesman for the Independent Election Commission, said preliminary results were due April 24 and final results will be announced May 14.

Electoral officials have urged patience, saying officials continued to log complaints and tally ballots. The ballots were coming from more than 20,000 polling stations nationwide, some in extremely remote and rural areas. They were being transported to tally centers in all 34 provinces before the results reach Kabul.