Abd al-Kadir Orire, secretary general of Nigeria's main Muslim representative body the Jama'atu Nasril Islam, said: "Between 200 and 250 people were killed in the violence, while many have disappeared."
"Those who disappeared cannot be accounted for, nobody knows if they are dead or in hiding. 120 people including women and children are missing," he said on Wednesday, citing the testimony of refugees fleeing the flashpoint town of Shendam.
"There are difficulties in getting exact figures because the situation is still tense, and it will take time to account for the exact number of dead and missing. It's mass murder, because machine guns were used, not machetes."
Late on Sunday, heavily armed fighters from the Christian Tarok ethnic group stormed Yelwa, a farming community in the Shendam local government area of central Nigeria's Plateau State, 300 km east of Abuja.
According to witnesses who fled the scene, some of the Christian fighters sprayed the town with heavy-calibre automatic fire from machine guns mounted on two jeeps, while others armed with machetes and rifles razed homes and attacked residents.
"It's mass murder, because machine guns were used, not machetes"
Abd al-Kadir Orire,
secretary-general, Jama'atu Nasril Islam
Plateau State Police Commissioner Innocent Iluozoke on Tuesday said that two mosques in the mainly Muslim Hausa-speaking community were damaged and that police had recovered 67 bodies, while more had been buried by local people.
Meanwhile, Nigeria's President Olusegun Obasanjo has sent 600 heavily armed police reinforcements to back up Iluozoke's peacekeeping efforts in the southern portion of Plateau, which has long been prey to ethnic violence.
The Tarok are mainly Christian and are subsistence farmers, while their Hausa and Fulani rivals are often nomadic herdsmen, whose livestock threaten their neighbours' crops. Both groups claim ancestral rights to the land.
There have been several recent reports of large-scale massacres in Plateau State and neighbouring Taraba State, but accurate casualty tolls are hard to obtain in a remote and permanently unsafe area of the country.