Soldiers patrolled the central Nigerian city of Jos on Monday and aid workers tried to assess the death toll after attacks on outlying communities in which several hundred people were feared to have been killed.

Acting President Goodluck Jonathan called an emergency meeting with all security service chiefs on Monday to discuss strategies to prevent clashes spreading to neighboring states, presidential sources said.Residents of three predominantly Christian settlements near Jos said Muslim herders from surrounding hills launched what appeared to be reprisal attacks in the early hours of Sunday following sectarian clashes which killed hundreds in January. A Reuters witness counted more than 100 bodies on Sunday in Dogo Nahawa, one of the three communities attacked.But victims were also brought to hospitals in Jos and some were quickly buried, making it difficult for officials to assess the toll.“Soldiers are patrolling and everywhere remains calm ... We are estimating 500 people killed but I think it should be a little bit above that,” Plateau State Commissioner for Information Gregory Yenlong said.Police spokesman Mohammed Lerama said the number of dead officially recorded so far stood at 55.Death tolls have been highly politicized in previousoutbreaks of unrest in central Nigeria, with various factionsaccused of either exaggerating the figures for political endsor downplaying them to try to douse the risk of reprisals.A Red Cross spokesman said the security situation was “still in disarray” and that while its teams had been able to help evacuate some people to hospital in Jos, they were still trying to reach all those areas affected.The latest unrest in the centre of Africa's most populous nation comes at a difficult time for Jonathan, who is trying to assert his authority while ailing President Umaru Yar'Adua remains too sick to govern.Tense regionPlateau state lies at the crossroads of Nigeria's Muslim north and Christian south and fierce competition for control of fertile farmlands between indigenous groups and settlers from the north have repeatedly triggered unrest over the past decade.The instability underscores the fragility of Africa's top energy producer as it approaches the campaign period for 2011 elections with uncertainty over who is in charge.Yar'Adua returned from three months in a Saudi hospital, where he was being treated for a heart condition, almost two weeks ago but has still not been seen in public. Presidency sources say he remains in a mobile intensive care unit.Jonathan put the security forces on red alert late on Sunday to try to prevent reprisal attacks spreading into neighboring states. He ordered the security forces to “confront and defeat these roving bands of killers.”Soldiers have been on the streets of Jos policing a dusk-to-dawn curfew since four days of clashes between Christian and Muslim mobs in January, when community leaders put the death toll at more than 400.France condemned the violence and backed Nigerian authorities.“France firmly condemns the serious violence,” French Foreign Minister Bernard Kouchner said in a statement. “I express France's support to the Nigerian authorities in their efforts to restore calm and bring the perpetrators of the violence to justice.” 09 March 2010, TuesdayREUTERS  JOS