An attack on Thursday on the airport and military airbase in Niger's capital killed 11 members of the security forces and two civilians, the government said in a statement, without identifying the perpetrators.
The first explosions were heard at around 6:00 AM local time (0500 GMT), witnesses said, and sporadic gunfire was still audible nearly two hours later at the airport in Niamey, which was targeted by the regional IS affiliate in January.
There was no immediate claim of responsibility for Thursday's attack.
Government forces repelled the attack and killed 22 assailants, while about 20 people were arrested and assorted weapons seized, according to the statement which was read out on state television.
The situation appeared mostly calm by midday, with only sporadic gunfire possibly linked to the army's sweeping operations, a Reuters witness and two residents said, noting that security forces had blocked off the area.
"Everything is under control," the government statement said.
Niger's civil aviation agency said in a separate statement that normal operations at the airport had resumed.
Niger, like its Sahel neighbours Mali and Burkina Faso, has struggled to contain attacks from groups linked to Al Qaeda and IS that have killed thousands and displaced millions across the three countries.
In claiming responsibility for the attack in January, West Africa's IS affiliate said it had targeted air command headquarters and drone assets and claimed to have "delivered a direct blow" to Niger's counterinsurgency operations.
The airport and military airbase are in the same complex, with the base situated opposite the civilian terminal.
On Thursday, assailants arrived at the airport in two white vehicles, a security source in Niger said.
A second security source said a group of attackers was hiding in a customs building near the airport.
On Wednesday, militants launched coordinated attacks on Banibangou and Inates military bases located in the western Tillaberi region, the security sources said.
One of the security sources put the death toll in Banibangou at 10 with more than 40 injured and said that the military had abandoned its base in Inates.
It was not immediately clear how those attacks may have been linked to the explosions and fighting in Niamey.
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