Soldiers were arrested in after an "attempted coup" early Wednesday, a security source said after g, adding "the situation is under control".
Residents reported hearing overnight bursts of gunfire near the presidency, just two days before Mohamed Bazoum is due to take the helm of the .
"There were some arrests among a few members of the army who are behind this attempted coup," said the source, speaking on condition of anonymity.
"The Presidential Guard retaliated, preventing this group of soldiers from approaching the presidential palace," said the source.
A resident of , which includes the president's official residence and offices, told AFP: "It was around 3.00 am, we heard shots from heavy and light weapons and it lasted 15 minutes before stopping, followed by shots from light weapons."
"The gunfire lasted about 20 minutes," another resident said.
A third resident spoke of "intense shooting, with heavy and light weapons".
Online newspaper actuniger.com reported that calm had returned by around 4.00 am.
In short video clips posted on social networks, only several seconds in length, sporadic bursts of gunfire could be heard in the pitch dark.
It was not yet possible to independently verify the location and timing of the videos.
The alleged coup comes ahead of Bazoum's scheduled inauguration on Friday -- the first elected transition in Niger's history since independence from France in 1960.
Bazoum is a former interior minister and right-hand man of outgoing president Mahamadou Issoufou, who is voluntarily stepping down after two five-year terms.
His victory in the second round of the election on 2 February was confirmed by the constitutional court this month.
The results were contested by Bazoum's rival, former president Mahamane Ousmane, who claimed he was the real winner.
Ousmane had called for "peaceful marches" across the country, but a planned opposition protest Wednesday in Niamey was banned a day earlier by authorities.
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Niger is the poorest country in the world, according to the benchmark of the UN's 189-nation Human Development Index.
It has suffered four coups in its history, most recently a February 2010 putsch which toppled then president Mamadou Tandja.
The Sahel country has also recently been struck by repeated jihadist attacks as Islamist movements have spilled over from neighbouring Mali and Nigeria.
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