Fierce competition for control of fertile farmlands between Christian and animist indigenous groups and Muslim settlers from the north have repeatedly sparked violence in central Nigeria's Middle Belt over the past decade.

Security forces said they had restored calm but a night curfew in Jos continued.

"We now have the traditional chief and the youth leader of the  area are with us and they are helping us with our investigation," Mohammed Lerama, the Plateau police spokesman, told the AFP news agency.

The latest killings have triggered fears of renewed clashes in Africa's most populous country, where religous clashes often result in the deaths of hundreds.

Sporadic violence killed at last nine people last week, seven of them discovered in shallow graves around 30km south of Jos.

Residents said they were killed after stopping at a roadblock set up by a local gang.