Incumbent President Ibrahim Boubacar Keita failed to reach the 50 percent threshold in the first round vote in the West African state. Eighteen candidates have said they will not accept results marred by irregularities.
The preliminary election results provided by the government on Thursday showed President Ibrahim Boubacar Keita won 41.4 percent of the vote in Sunday's election in his bid for a second term in the landlocked state.
Keita's nearest challenger, former finance minister Soumaila Cisse, won 17.8 percent, according to the Ministry of Territorial Administration.
Turnout was 43.06 percent and 644 polling stations, about 3 percent of the total 23,000, were shut down by armed attackers. About 20 percent of polling stations were affected by violence, the Ministry declared.
As neither candidate reached the 50 percent threshold, a second round vote between Keita and Cisse will be held on Sunday August 12.
Cisse was one of 18 candidates who signed a declaration on Wednesday, saying they would not accept the results, alleging corruption, vote buying and ballot stuffing.
"We will not accept results marred by irregularities," the group of 18 of the 24 candidates said in their statement.
Cisse's campaign director, Tiebile Drame, said: "We do not want to delegitimise the entirety of the process but there needs to be a minimum of credibility. There was a "village of 150 inhabitants where 3,000 people voted" for Keita, Drame said.
Observers from the European Union, the African Union and the regional Economic Community of West African States (ECOWAS) were in Mali for Sunday's vote.
European observers and opposition candidates have asked the government to publish a list of polling stations where it was not possible to hold the election because of violence.
Islamist militants, some allied to al Qaida and Islamic State groups, have been in control of parts of northern Mali since 2012.
Mali is the eighth-largest country in Africa with a population of 17.9 million.
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