Niger's President Mahamadou Issoufou has said his government has foiled a plot to overthrow him.
Mr Issoufou said the plotters planned to use "aerial firepower" to unseat him, in comments made on state TV.
He was elected in 2011, bringing to an end years of military rule. Niger has seen several coups since becoming independent in 1960.
Tensions are high ahead of next year's presidential election, which Mr Issoufou is favourite to win.
"The government has just foiled an evil attempt at destabilisation," he said.
"The objective of these individuals, motivated by I don't know what, was to overthrow the democratically elected power."
An investigation has been launched to identify those responsible and possible accomplices, he added.
At least four senior military officials have been arrested in relation to the incident.
Shortly after Mr Issoufou's election in 2011, 10 military figures were arrested for allegedly plotting to assassinate him.
Niger is rated by the UN as one of the world's least-developed nations and on Thursday, it was named as the worst country to live in.
Analysis: Baro Arzika, BBC Africa, Niamey
Even though no military or government facility was attacked by those accused of plotting to overthrow the administration of Mr Issoufou, the president appears to be taking the issue seriously.
Some high-ranking military officers have been arrested and linked to the plot. More arrests are expected in the coming days.
Some people will however be relieved that the president has not linked the alleged coup attempt to the ongoing political crisis between him and the opposition over the preparation of next year's poll.
The opposition has accused the ruling party of interfering in the electoral process, which it denies.
Most people I have spoken to were shocked and dismayed about what they consider as yet another attempt to scuttle the country's fragile democracy.
People here are well aware of Niger's history of military coups.
Even the election that brought the current government to power was organised by a military junta which in 2010 overthrew President Mamadou Tandja, after he had attempted to change the constitution and extend his rule.
More about Niger
The Republic of Niger
Population 16.6 million
Area 1.27 million sq km (489,000 sq miles)
Major languages French (official), Hausa, Songhai, Arabic
Major religions Islam, indigenous beliefs
Life expectancy 55 years (men), 56 years (women)
Currency CFA (Communaute Financiere Africaine) franc