Zimbabwe's opposition Movement for Democratic Change (MDC) has won a March 29 presidential election.
Lovemore Sekeramayi, chief elections officer of the Zimbabwe Electoral Commission (ZEC), said on Friday that Morgan Tsvangirai, leader of the MDC, had 47.9 per cent of the vote, beating Robert Mugabe, the president, with 43.2 per cent.
But the MDC faces a second-round vote after its leader failed to garner enough votes against Mugabe.
"Since no candidate has got the majority of the valid vote, a second election shall be held on a date to be advised by the commission," said Sekeramayi.
Under Zimbabwe election law, the run-off has to be held within 21 days after the announcement of the result.
Simba Makoni, a former finance minister widely expected to back Tsvangirai in any run-off, came third in the vote with 8.3 per cent, Sekeramayi said.
The MDC rejected the results of the March 29 presidential election as deadlocked all-party talks hosted by the electoral commission resumed in the capital, Harare, on Friday.
The MDC claims its leader got 50.3 per cent of the vote, an outright majority needed to avoid a run-off.
"We don't agree with their figures. They will have to prove us wrong. We are now going into the verification of those figures," Chris Mbanga, an MDC representative said on Friday.
Haru Mutasa, Al Jazeera's correspondent reporting from Harare, said that the MDC considers the 47.9 per cent figure to be "wrong" and that it "should have been in the 50s".
"They [opposition] are saying that the ZEC rigged the numbers to ensure that there is a run-off," she said.
"They also saying that if they take part in the run-off they will not be allowed to campaign freely and that their supporters would be further intimidated [by security forces]."
On Thursday, Mugabe expressed readiness to contest a presidential run-off and promised to accept the result, urging the opposition to take the same approach.
Mugabe made the pledge during a meeting with Cheikh Tidiane Gadio, Senegal's foreign minister.
The meeting discussed the tense poll standoff and the need to divulge the results of the March 29 presidential election.
The Senegalese foreign ministry released a statement after the meeting saying that Mugabe had agreed to stand for a run-off "in good faith and the firm will to accept the will of the people delivered in a free and fair election".
The statement said that Mugabe had also assured Gadio that he would "unhesitatingly accept the results of the second round and urged the opposition to take the same approach".
Tsvangirai has suggested he could still take part in a second round if international observers led by the United Nations monitored the process.
The main international observer group at the first round was from Zimbabwe's neighbours.
If he refuses to take part in a run-off, Mugabe will be declared the winner.
The MDC has also accused the government of launching a campaign of violence and intimidation ahead of the possible second round and said 20 of its members had been killed by pro-government militias.
On Thursday, Tsvangirai told France 24 television that post-election violence had made it impossible to hold a second round run-off.
"How can you have a run-off when Mugabe over the past month has been unleashing violence, death squads and violence against our structures," he said from Johannesburg in neighbouring South Africa.
Human rights groups have accused the government of using the army and so-called "war veterans" of using the delay in publishing the results to intimidate opposition supporters before a possible run-off.
The government has dismissed the accusations.