Nigeria's air force said it was investigating reports of civilian casualties during a weekend air strike that targeted armed gangs in the northwest, the latest military operation where innocent people may have been accidentally killed.

The army and air force have increasingly used aerial assaults against the growing threat in the northwest and central region posed by armed criminal gangs, known locally as bandits, that kill villagers and carry out mass kidnappings.

Nigerian Air Force (NAF) spokesperson Air Vice Marshal Olusola Akinboyewa said late on Sunday an air strike in northwestern Zamfara state on Saturday had targeted bandits, and that the air force had managed to rescue kidnapped victims.

But residents told Reuters that at least 15 civilians, including local security guards, were killed.

An investigation into the matter was being conducted, Akinboyewa said in a statement.

Air strikes have inadvertently killed civilians before. In December, at least 10 people were killed after a military fighter jet pursuing bandits mistakenly bombed civilians in northwestern Sokoto state.

Akinboyewa said the NAF would work to minimise and prevent any harm to civilians and civilian infrastructure in its operations.

Nigeria's Chief of Defence Staff General Christopher Musa told local television on Monday that the military did not intentionally target civilians and that the Zamfara incident would be fully investigated.