Hillary Clinton seeks Nigeria trial for Jos massacres
Mark Lipdo of the Stefanos Foundation said he witnessed the massacre
US Secretary of State Hillary Clinton has urged Nigeria to arrest and try those responsible for killing hundreds of people near the city of Jos.
The massacre is seen as revenge for a previous round of killings in January.
Human Rights Watch says the violence has continued because no-one has been held accountable in the past and "it is time to draw a line in the sand".
Nigerian troops are patrolling the villages which were targeted on Sunday in a bid to prevent further violence.
Acting President Goodluck Jonathan has sacked the country's national security adviser, Sarki Mukhtar in an apparent response to the killings.
Some have questioned how the attack could have taken place when a military curfew has been in place since January, when at least 200 people died in clashes between rival Christian and Muslim groups.
Christian leaders complained that it took the army two hours to react to a distress call.
The Plateau State Christian Elders Consultative Forum told AFP news agency that by that time, "the attackers had finished their job and left".
Caroline Duffield, BBC News, Lagos
Already this is being described as retaliation for the outburst of killing in January in which hundreds more people were killed.
Back then the largest losses were suffered by the Hausa Fulani community. In the village of Kuru Karama more than 100 people were killed and their bodies thrown into wells and sewers. Grave accusations were made that the local government had stoked the violence. This time it is clear that the targets were Berom Christians.
For weeks there have been rumours of retaliation in these villages and people have been living in a state of anxiety. Many families left. These killings are often painted by local politicians as a religious or sectarian conflict. In fact it is a struggle between ethnic groups for fertile land and resources in the region known as Nigeria's Middle Belt.
Many of the dead in the villages of Zot and Dogo-Nahawa, largely inhabited by Christian members of the Berom community, are reported to be women and children.
The latest attacks are said to have been reprisals for the January killings when many victims were Hausa-speaking Muslims.
The authorities say the villages are now calm after troops and military vehicles entered them.
Mrs Clinton also urged the authorities to ensure that the army respected human rights as it restored order - Nigeria's security forces have a reputation for brutality.
"The Nigerian government should ensure that the perpetrators of acts of violence are brought to justice under the rule of law, and that human rights are respected as order is restored," she said.
"This kind of terrible violence has left thousands dead in Plateau State in the past decade, but no-one has been held accountable," said Corinne Dufka from US-based lobby group Human Rights Watch.
Officials from the Christian-dominated state government say that up to 500 people were killed but others say the death toll might have been exaggerated. Dozens of arrests have already been made, say officials.
Chief Gabriel Gyang Bot, from nearby Shen, told the BBC's Focus on Africa programme that people in his village feared more attacks.
He said he had received text messages from people who claimed responsibility for the weekend attacks and had threatened to return.
In January, religious leaders blamed inflammatory text messages for fuelling the violence.
Mark Lipdo, from the Christian charity Stefanos Foundation, said Zot village had been almost wiped out.
JOS, PLATEAU STATE
Deadly riots in 2001, 2008 and 2010
City divided into Christian and Muslim areas
Divisions accentuated by system of classifying people as indigenes and settlers
Hausa-speaking Muslims living in Jos for decades are still classified as settlers
Settlers find it difficult to stand for election
Communities divided along party lines: Christians mostly back the ruling PDP; Muslims generally supporting the opposition ANPP
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