The mutinous soldiers attacked the airport and the presidency in Niamey overnight, triggering hours of gunfire and explosions and briefly knocking state television and radio off air.
By late Saturday morning, Niger's defence ministry said the armed forces were gradually retaking sites seized in the overnight attack, but security sources said mutineers were still at the airport in the afternoon and the overall situation remained unclear on Saturday night.
It was the culmination of nearly 24 hours of unrest that appeared to be staged by young soldiers aggrieved over the worsening militant violence under the country's military junta. Russia's Africa Corps provided aerial and ground support to local forces to resist the rebellion, according to analysts and diplomats.
State broadcaster RTN showed footage of dozens of mostly young soldiers being paraded in public after sustained gunfire and explosions were heard overnight into Saturday at a key military base located within Niamey's main airport and near the presidential palace.
The attack marked the latest threat to the rule of Abdourahamane Tiani, who seized power in a 2023 coup. Tiani had pledged to improve security in the Sahel nation, a major uranium producer, but jihadist attacks have persisted.
The whereabouts of Tchiani were unclear.
State television, after resuming broadcasts, aired a message saying mutinous soldiers from a base in Niamey had opened fire on "sensitive sites" in the city.
Security forces had reacted quickly and "contained this disturbance", it said.
Earlier this year, affiliates of al Qaeda and Islamic State carried out attacks on the civilian airport and military airbase. Some security observers initially suspected militants were behind Saturday's assault.
Tiani made no public appearances on Saturday.
Even if he survives the mutiny, the unrest raises the prospect that resources otherwise spent fighting jihadists will need to go towards policing internal threats, said Heni Nsaibia, senior analyst for West Africa of Armed Conflict Location & Event Data (ACLED).
"The jihadist groups will be the only winners in this situation," he said.
A Reuters witness reported gunfire at the airport and military airbase, where Russian and Italian forces are stationed, and heavy explosions in the pre-dawn hours.
The presidential palace appeared to have been secured by loyalist troops but the area around the airport was still contested, two security sources and a diplomat said.
The defence ministry statement referred to an effort by the mutineers "to detain some of their comrades" at the military airbase, without providing details.
Two sources said loyalist troops had been dispatched to retake control of the airport, either through negotiations or by force.
The Alliance of Sahel States, made up of Niger, Mali and Burkina Faso, voiced support for Niger's military and said in a statement on Saturday night that the mutineers had been thwarted. It was unclear whether Mali and Burkina Faso provided any concrete military support to Niger on Saturday.
The mutineers' operation also involved soldiers from the localities of Ouallam, Tera and Dosso in the southwest, according to a Niger security source and Yvan Guichaoua, senior researcher at the Bonn International Centre for Conflict Studies.
Troops in this area have sustained heavy casualties in battles with the regional Islamic State affiliate. Analysts and security sources say frustration with the government is mounting within frontline units.
"Just a week ago, some 18 soldiers were killed in an attack on their position in the southern Dosso region. These mass-casualty overrun attacks on the Nigerien military are becoming commonplace and will continue to fuel unrest and aggravate tensions within the army ranks," Nsaibia said.
It was not clear how many troops allied with the mutineers had entered Niamey or where they had deployed.
with AP