Former Malian finance minister Soumaila Cissé on Monday conceded defeat against ex-prime minister Ibrahim Boubacar Keita in Mali's presidential election.
"I went to see him to congratulate him and wish him good luck for Mali," Cissé told Agence France-Presse (AFP) before official results were announced.
Electoral and security sources earlier said Keita had pushed ahead with two thirds of votes counted after Sunday's second round of the election.
Mali's government has until Friday to make public the result of the run-off, called after none of the 27 candidates secured an outright majority in the first round, held July 28.
Keita – widely known as IBK – faced Cissé in the election run-off, which is to provide a fresh start for the West African nation following more than a year of political turmoil, including a military coup and war.
"With nearly two thirds of the ballots counted, IBK is well ahead," said a source close to Mali's election commission, which helped organise the polls.
Unofficial estimates obtained by AFP from Malian security sources also put Keita (68) comfortably in the lead.
But Gouagnon Coulibaly, Cissé's campaign manager, said there had been "massive fraud" during the election, without elaborating, and accused the transitional government of being "partisan" in favour of Keita.
'Credible and transparent' election
The election, the first since 2007, was seen as crucial for unlocking more than $4-billion in aid promised by international donors who halted contributions in the wake of last year's coup that ignited an Islamist insurgency and a French military intervention.
The government has until Friday to make public the result of the run-off, called after none of the 27 candidates in the first round on July 28 secured an outright majority.
Voting was hampered by heavy downpours in the capital Bamako, and the European Union's election observation mission gave an estimated turn-out of "around 45%", lower than the 48.9% achieved in the first round but still significantly higher than in previous elections.
The mission said voting had complied with international standards in "99%" of Mali's polling stations.
"Whoever is elected will be elected with democratic legitimacy. That is my belief," mission chief Louis Michel told reporters in Bamako, adding that there had been "a leap forward in terms of democracy in this country".
In Brussels, European Union foreign policy chief Catherine Ashton welcomed what she called "a credible and transparent" election, according to a statement from her office released in French.
She urged all the candidates and parties to accept the outcome and "support the future government in the efforts it must make to build a durable peace and restore national unity".
Ashton pledged EU support for such efforts.
France's troops in Mali
Keita and Cissé (63) lost out in 2002 to Amadou Toumani Touré, who was overthrown by a military junta in March last year just weeks before the end of his final term in office.
The return to democratic rule will allow France to withdraw most of the 4 500 troops it sent to Mali in January to oust Al-Qaeda-linked extremists who had occupied the north in the chaos that followed the coup.
Keita had been more than 20 percentage points ahead of his rival in the first round but Cissé complained about widespread fraud.
Mali's Constitutional Court rejected the allegations, however, confirming that Keita had won 39.8%, while Cisséattracted a 19.7% share.
Keita claimed to have the support of 22 of the 25 candidates eliminated in the first round and was backed by Mali's influential religious establishment, while Cissé was endorsed by Adema, Mali's largest political party.
The country of more than 14 million remains the continent's third-largest gold producer, but its $10.6-billion economy contracted by 1.2% last year. Widespread poverty has contributed to unrest in the north, with several armed groups vying for control in the vacuum left when the Islamists fled.
The region is home predominantly to lighter-skinned Tuareg and Arab populations who accuse the sub-Saharan ethnic groups that live in the more populous and prosperous south of marginalising them.
A UN peacekeeping mission integrating more than 6 000 African soldiers was charged with ensuring security on Sunday and in the months after the election. By the end of the year it will have grown to 11 200 troops and 1 400 police.
Meanwhile, the United States signalled on Monday that it was prepared to resume aid to Mali following a presidential election that paved the way for the return of a democratically elected government.
Marie Harf, deputy spokesperson at the state department, hailed the country's interim government for "securing a peaceful and orderly environment in which Malians were able to vote."
While urging patience in the formal ballot-counting process in the run-off between the top two contenders, Harf suggested that a resumption of US aid was likely.
"We've made clear that following the return of a democratically elected government, we will seek to normalise our foreign assistance to Mali," she told reporters in Washington.
"These programmes will be reviewed and revised to assess the security and development needs in the light of the new environment."
The United States was legally forced to suspend military aid to Mali after the coup in March last year. – AFP