Jos - Nigeria must prosecute those behind a weekend massacre and address underlying issues of poverty and discrimination if it is to end a cycle of violence in the zone between its Muslim north and Christian south, rights groups and diplomats said.

The United Nations, United States, rights groups and opposition politicians all urged the authorities to ensure those responsible face justice after attacks on Sunday on three Christian villages in which hundreds are feared to have died.

Residents of Dogo Nahawa, Zot and Ratsat, about 15 km (9 miles) south of the central city of Jos, buried dozens of bodies including those of women and children in a mass grave on Monday following the attacks, which they blamed on Muslim herders.

The raids were in apparent retaliation for four days of violence around Jos, the capital of Plateau state, in January which killed several hundred people, many of them in an attack on the mostly Muslim settlement of Kuru Karama.

The latest unrest at the heart of Africa's most populous nation comes at a turbulent time, with Acting President Goodluck Jonathan trying to assert his authority while ailing President Umaru Yar'Adua remains too sick to govern.

Jonathan deployed troops to quell January's unrest and pledged that those found to have "engineered, encouraged or fanned" the violence would be brought to justice.