Sporadic violence in Nigeria's central Plateau state has killed at least nine people this week, Reuters quoted police and residents as saying, as tensions remained high weeks after hundreds died in sectarian clashes. Seven bodies were found on Tuesday in shallow graves in the Riyom area, around 30 km (20 miles) south of Jos. Residents say they were killed after stopping at a road block set up by a local gang. In a separate incident, security forces killed two Nigerians suspected of planning an attack in a village near Plateau state's capital Jos, which lies at the crossroads of the country's Muslim north and Christian south. "The roads to Jos are not safe," said Muhammad Tanko Shittu, a senior mosque official in Jos. "We are telling our youths not to hold any protests over these attacks because it may lead to further killing." Security forces have been on high alert for any violence in the state, fearing a repeat of clashes between Muslim and Christian mobs that led to hundreds of deaths in January and March. 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 say they have the situation under control, maintaining a night curfew in Jos. -- SPA