Mali's opposition leader on Friday rejected the announcement that President Ibrahim Boubacar Keita was the winner of a presidential runoff in this West African nation, saying he would be filing a fraud complaint to the Constitutional Court.Soumaila Cisse held a news conference to declare that, according to results from his party, Cisse instead won the runoff with 51.75% of the vote to Keita's 48.25%."I reject the results proclaimed by the Ministry of Territorial Administration that do not reflect the vote of Malians," Cisse said.The Constitutional Court has until August 22 to approve the election results.The Ministry of Territorial Administration said Thursday that Keita won a second five-year term in the turbulent nation, capturing more than 67% of the vote to Cisse's 32%.More than 2.7 million Malians voted in Sunday's runoff, a 34% turnout despite threats by extremist groups.European Union observers said there were irregularities during Sunday's vote but did not say there was fraud.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and FacebookAfter the declaration of the results, Keita received congratulations from French President Emmanuel Macron, whose military has been engaged in Mali in the fight against extremism.The UN Secretary General Antonio Guterres also called 73-year-old incumbent to congratulate him. The UN has had more than 12 000 peacekeepers in the turbulent country since 2013.As Keita supporters celebrated Thursday night, the capital city of Bamako experienced a restless night. Cisse supporters marched with anti-Keita signs, denouncing the results."We are launching a vibrant call for citizen mobilization to exert popular, peaceful and democratic pressure to enforce the Malian vote," said Cisse campaign director Tiebile Drame.Mahamadou Camara, spokesperson for Keita, had called the victory well-earned.Keita leads a nation that has grown more insecure since he beat Cisse in a second-round election in 2013, the same year that French-backed forces pushed extremists in the north from their strongholds. Keita took power the year after a military coup ushered in an era of chaos that allowed the extremists to flourish.Heavy-handed counterterror operationsThe extremists linked to both al-Qaeda and the Islamic State group have been staging more brazen attacks that have spread into central Mali. Deadly communal clashes between ethnic groups and accusations of heavy-handed counterterror operations have caused even deeper tensions and mistrust of the government.In northern and central Mali, more than 50 polling stations had closed before noon on Sunday because of threats by extremists, according to the Citizen Observation Pool of Mali, which had more than 2 000 observers.The observers also reported several incidents of violence on voting day, including the killing of a village chairman and the harassment of at least four election workers. A number of polling stations were burned.