At least 30 people were killed in attacks by armed men on several villages in Nigeria's northwestern state of Sokoto on Saturday, police said.

Police in Sokoto said the people killed belonged to a vigilante group in the Tangaza local government area. Prior to the attacks, some members of the vigilante group went to the Azam village of the area to warn the community there against possible violence

"On getting the information that assistance was coming, the vigilantes withdrew to their various villages," it said.

However, the gunmen went after the vigilante members and killed eight in Raka, seven in Bilingawa, six in Jaba, four in Dabagi, three in Raka Dutse, and two in Tsalewa villages, the statement said.

Armed attacks have been a primary security threat in parts of Nigeria, leading to deaths and kidnappings in recent months.