Flights resumed amid tight security Friday at the international airport in Niger's capital, Niamey, a day after a deadly attack on the sensitive site.

Gunmen opened fire near the airport entrance's security checkpoint early Thursday, triggering a long battle with security forces that spilled into the surrounding area and left at least 11 soldiers and two civilians dead, as well as 22 attackers, according to the defence ministry.

Al-Qaeda's branch in Africa's Sahel region, JNIM said it carried out the attack - the second this year on the airport, after a January 29 assault claimed by a terrorist group affiliated to the Daesh.

Tracking site Flightradar24 indicated multiple flights bound for Niamey had been rerouted or delayed after the unrest erupted, but sources said Friday normal operations had resumed, with a heavy security deployment.

"Everything has resumed normally," with security "reinforced", an airport source said.

Suspects arrested

An airline employee confirmed flights had resumed, saying two companies' planes had arrived Thursday after security forces repelled the attack.

The defence ministry said the attackers had been dispersed into surrounding neighbourhoods, where residents helped security forces chase them down.

"Things got intense. We hunted those bandits down with no mercy," said a resident of the Route Tchanga neighbourhood.

Around 20 suspects were arrested, officials said.

Niamey announced widespread security checks on the city's roads.

The Niamey airport is a sensitive site: between December and January, a large cargo of concentrated uranium from the key producer was blocked at the facility while waiting for export.

No movement of that cargo has since been identified.

In January's airport attack, 20 assailants were killed and four soldiers wounded, according to authorities.