Former Malian Prime Minister Ibrahim Boubacar Keita holds a comfortable lead and could win an outright first-round victory in the West African nation's presidential election, according to preliminary results released by a government official.
The final result should be announced later on Wednesday.
Keita's rivals immediately rejected the partial results, calling for the minister of territorial administration, who is in charge of the elections and made the statement on Tuesday, to resign and an international commission to be established to tally the vote.
They are demanding that the vote go to a second round.
Voting in the polls on Sunday was peaceful and observer missions have praised the process, but tensions rose as the announcement of results neared.
"There is one candidate, Ibrahim Boubacar Keita, who has a wide margin compared with the other candidates," Colonel Moussa Sinko Coulibaly, the minister of territorial administration, told journalists in the capital, Bamako.
"If maintained, [it means] there will not be a need for a second round," he said. The results represented a third of ballots cast from constituencies across the country, he said.
Amadou Koita, spokesman for ex-Finance Minister Soumaila Cisse, who Coulibaly said was currently in second place, called the announcement "scandalous" and questioned why the minister refused to give figures to back up his statement.
Koita questioned how the minister could give a projection based on one-third of votes when he said the commission that is made up of representatives from all camps and is tasked with collating results had only counted 12 percent of votes so far.
Complaints about process
Minutes after the results were announced, cars and motorcycles on the streets of Bamako honked their horns and Keita's supporters outside his house chanted "IBK, IBK, IBK!" the initials he is universally known by.
Al Jazeera's Nazanine Moshiri, reporting from Keita's campaign headquarters in Bamako, said that celebrations had begun there.
"The celebrations have already started here, even though only a third of the results have come out. People here believe he has won the election, he will become the next president of Mali," she said.
"But the opponents of Ibrahim Boubacar Keita say that it is too early for him to declare victory, that they will be opposing it in the courts [...] the United Nations has called on all sides to respect the final outcome and has called this election successful and legitimate."
Cisse and two other of Keita's rivals - Modibo Sidibe, a former prime minister, and Dramane Dembele, the candidate of Mali's biggest party - came together on Monday to complain about the process.
Their FDR coalition, which was initially set up to counter last year's military coup, complained that hundreds of thousands of people had been excluded from the vote due to technical shortcomings.
Members of the FDR coalition have claimed that world powers led by France, which pushed for the vote to be held despite concerns over Mali's readiness, favoured Keita in the process.
Cisse said he would challenge the results if Keita is announced winner in one round.
"It is up to Mr Cisse to prove what he claims and to use the legal existing channels for his claim. The imperfections will affect the winners as well as the losers," Louis Michel, the European Union's chief observer to the Mali mission, said on Tuesday.
Average turnout was tallied so far at 53.3 percent, well above Mali's record high of 40 percent, Coulibaly said. Final results could be ready on Wednesday.
Whoever wins the election will have to push through national reconciliation efforts and conclude peace talks with Tuareg separatist rebels who allowed the vote to take place but are still armed in remote corners of Mali's desert north.
They will also oversee a $3.98bn plan proposed by donors to rebuild the nation and kick-start the economy.