Soldiers rushed to restore calm to parts of central Nigeria on Tuesday with 18 people reported killed as renewed violence flared in the tense region, authorities said.
Central Nigeria has seen a wave of violence in recent weeks, including Christmas Eve bomb blasts and reprisal attacks that killed at least 80 people as well as clashes between Christian and Muslim ethnic groups.
The surge in killings has occurred ahead of elections set for April.
"I am told that 13 people died in the dawn attack," Plateau state police commissioner Abdulrahman Akano said of one attack in the mainly Christian village of Wareng.
A local politician also said 13 were killed there, adding they had been hacked to death with machetes.
A separate attack in the nearby area of Barkin Ladi left five more people dead, Akano said later in the day without providing further details.
The commander of a military task force in the region said unrest had occurred in various areas and soldiers were deployed to restore calm.
"We have quite a number of people killed," Brigadier General Hassan Umaru told AFP. "We are trying to contain each of these crises."
He could not immediately provide details on the unrest. Umaru first reported incidents in "several villages," but later said two villages had been hit.
The local politician, Emmanuel Danboyi Jugul, alleged Fulani Muslims had attacked Christian Beroms in the Wareng attack. He also accused soldiers of being involved in the attack, though Umaru strongly denied the claim.
Plateau state, including its capital Jos, has long been on edge, but unprecedented Christmas Eve bomb blasts added a frightening new dimension to the unrest.
An Islamist sect blamed for a series of attacks in the country's north claimed responsibility for the Christmas Eve explosions, but authorities cast doubt on the claim and attributed it to political motives with elections set for April.
Plateau state lies in the so-called middle belt between Nigeria's mainly Muslim north and predominately Christian south.
Scores of people have been killed in clashes in the region in unrest many attribute to the struggle for economic and political power between Christian and Muslim ethnic groups.
Christians from the Berom ethnic group are typically referred to as the indigenes in the region, while Hausa-Fulani Muslims are seen as more recent arrivals.
Tensions over the weekend in the region left a number of houses burnt, while two buses carrying Muslim passengers were attacked in a Christian village on Friday.
Nigeria as a whole has seen an upsurge in violence in recent weeks ahead of the April elections, including a deadly bombing in the capital Abuja and violence targeting political rallies.