Authorities declared ruling party candidate Mohamed Bazoum winner of the run-off election but his rival, former president Mahamane Ousmane, has alleged fraud and also claimed victory.
Supporters of the losing candidate in Niger's presidential election have burnt tyres, threw rocks and set several buildings on fire in a third day of violent protests in the capital, Niamey.
Niger's electoral commission declared ruling party candidate Mohamed Bazoum the winner of Sunday's runoff election with 55.75 percent of the vote, but his rival, Mahamane Ousmane, a former president, has alleged fraud and claimed he won with 50.3 percent.
The election is meant to lead to the first transition from one democratically elected leader to another following four coups since independence from France in 1960.
President Mahamadou Issoufou is stepping down after two five-year terms.
En aucun moment le Président Mahamane Ousmane n’a souhaité, permis ou autorisé les manifestations en cours! pic.twitter.com/mv0nuAUcTU— Mahamane Ousmane, Président (@NafarkoMO) February 25, 2021
The national prosecutor said late on Wednesday that several people had been arrested in the protests. Internet access has also been severely limited since Wednesday.
On Thursday, small groups of Ousmane supporters again took to the streets to lob rocks at police and national guard troops, who responded by firing tear gas.
Some protesters set private houses on fire, including that of Radio France Internationale (RFI) correspondent Moussa Kaka, a Reuters witness said.
RFI said in a statement that Kaka and his family were safe and condemned what it called "a grave attack on freedom of the press".
Ousmane, who served as president from 1993 until 1996, when he was overthrown by the military, said on Wednesday that he reserved the right to appeal the election result in the courts.
An observer mission from the Economic Community of West African States has said the vote was held "under free, fair, credible and transparent conditions".
However, it was marred by two attacks that killed eight election workers in parts of Niger where Islamist militants regularly target civilians and the military.