MAIDUGURI( Reuters)-At least 30 people have been killed and several others injured in Nigeria's central Plateau state in a series of attacks around Mangu town, despite a curfew imposed by the state government, a community spokesperson said. Farmer-herder attacks and communal conflicts are rife in central Nigeria, an ethnically and religiously diverse hinterland known as the' Middle Belt' where a circle of violence has claimed hundreds of lives in recent years. The latest violence on Tuesday and