Gunmen killed at least 30 people in an attack on a mosque in northwestern Nigeria earlier this week, according to a resident and a lawmaker, raising an earlier toll of 13.

"Bandits", as members of criminal gangs are locally known, struck a mosque in the town of Unguwar Mantau, in Katsina state's Malumfashi local government area on Tuesday, with a conflict monitor reporting an initial toll of 13 dead.

"Nine worshippers were killed on the spot and many others died in the course of the day. The latest toll stands at 32," said resident Nura Musa said on Wednesday.

Local politician Aminu Ibrahim told the Katsina House of Assembly on Tuesday that 30 people had been killed.

A statement by Katsina State Commissioner for Internal Security and Home Affairs, Dr Nasir Muazu, said the attack was in retaliation for the community's successful defence two days ago, as the people of Unguwan Mantau ambushed terrorists and killed many of the bandits.

The government, meanwhile, said security agencies have been deployed to the area to restore normalcy.

Banditry in Nigeria's northwest and north-central regions poses a significant security challenge. The groups are known for their brutality, attacking villages, kidnapping residents for ransom and looting property.

President Bola Tinubu has taken a firm stance against bandits and terrorists in Nigeria in response.