Niger's government has foiled an attempted coup and arrested people who planned to use aerial firepower to seize control, President Mahamadou Issoufou said in an address on national television on Thursday.
Issoufou was elected in 2011, one year after a coup.
Political tension is high ahead of a presidential election set for Feb. 21. Issoufou is favourite to win but the opposition accuses his government of repression ahead of the vote.
Issoufou called the coup attempt high treason and said the situation was under control and all the main actors had been arrested, except one person who had fled. The people behind the coup held power in the 1960s, he said.
"The government has just foiled an evil attempt at destabilization. The objective of these individuals, motivated by I don't know what, was to overthrow the democratically elected power," he said.
"They envisaged using aerial firepower and they have for some weeks deliberately blocked [those military assets] in Niamey that I was pressing them to send to Diffa to the front for the struggle against Boko Haram," he said.
The West African country is a major uranium producer and Western ally in a regional fight against Islamist militants including Nigeria's Boko Haram. Niger has declared a state of emergency in its southeastern Diffa region due to numerous cross-border attacks this year from Nigeria.
Gendarmes arrested at least four senior military officers on Tuesday, military sources and family members of those detained said on Thursday.
Among those taken into custody were the former military chief of staff, General Souleymane Salou, and Lieutenant-Colonel Dan Haoua, head of the air force base in the capital Niamey.
"It's said they are suspected of wanting to carry out subversive activities, but nothing is clear for the moment," said a relative of General Salou.
Issoufou's election marked the restoration of democratic rule after a coup toppled his predecessor Mamadou Tandja.
The ruling Niger Party for Democracy and Socialism says it expects Issoufou to win in the first round.
Niger's main opposition party has chosen as its candidate former prime minister Seyni Oumarou, who came second at the last election.
A third candidate, opposition leader Hama Amadou, flew back to the country on Nov. 14 and was arrested on charges of suspected involvement in a baby-trafficking scheme.