"One of the most worrying things we're hearing is that some of those who survived the attacks are alleging that some of the attackers were dressed in Nigerian military fatigues."
She said the military was preparing a statement and would likely deny any involvement in the attack.
Reports from the scene said that many of the victims had deep machete cuts and had been partially burned.
At least three huts were also burned in the raid.
The attack happened despite a dusk-to-dawn curfew in Plateau state, which has been enforced by the military since January when hundreds of people, mainly Muslims, were killed in clashes in the region.
Earlier in March, more than 500 people, predominantly Christian villagers near the central city of Jos, were killed in an attack blamed on Muslim herders from nearby hills.
"Enough is enough. We don't want the military again," said Emmanuel Jugu, who represents Riyom in the Plateau parliament.
"We have been observing the curfew. So how can people now come and slaughter us. The military should withdraw. We are capable of defending ourselves."
Plateau, of which Jos is the capital, lies at the crossroads of Nigeria's Muslim north and Christian south, a region known as the "Middle Belt".
The repeated unrest has been attributed in part to fierce competition for control of fertile farmlands between Christian and animist indigenous groups on one side and Muslim settlers from the north on the other.
The unrest comes at a difficult time for Nigeria, with Goodluck Jonathan, the country's acting president, trying to consolidate power while Umaru Yar'Adua, the ailing president who recently returned from three months in a Saudi hospital, is too sick to govern.