Extremist Muslim herdsmen have slaughtered close to 500 Christian farmers in central Nigeria in a series of ongoing attacks over the last month.

The attackers are reportedly still hiding out in the villages, making it too dangerous for survivors to return and bury the dead.

"We have corpses littered in the field like a war fought in the Roman Empire by Emperor Nero," said Steven Enada, a development advocate campaigning against the killing, speaking to Morning Star News.

The slaughter has also left 7,000 Christian villagers displaced.

One survivor said he took the risk of coming to one of the villages with a delegation from the Nigerian president. "Entire villages were burned down completely by Fulani herdsmen. Unidentified corpses of these Christians were discovered, properties were looted by these Fulani invaders. As I speak to you, Fulani herdsmen are living in the deserted villages. I couldn't believe what my eyes saw," he said.

“Our people were massacred and houses burned down by the Fulani herdsmen,” said another survivor.

Leaders of the herdsmen said that the killings were in retaliation for the slaughter of 10,000 cows by the Christian farmers, a claim vehemently denied.

However, Emmanuel Ogebe, a human-rights lawyer who was part of a fact-finding mission, said logistically, killing such a large number of cattle would have been physically impossible for the Christian farmers.

"Such a mass slaughter would take weeks, and the skeletal remains of the cows would completely dot the landscape of Agatu, and the stench would permeate the air," he said.

Rather, Ogebe said he feels the motivation was religious jihad, with extremists planning to take over the villages, as evidenced by the fact that the herdsmen were still occupying the villages.

Andy Obeya, who was part of a relief team that visited the villages along with media and activists, said only Christians and church buildings were destroyed in the attack. “There was not a single burnt mosque, where everything else was razed,” Obeya said.

While corpses were found everywhere, Obeya noted the team observed thousands of live cattle grazing on people’s farms.

Sources report the killings are continuing in the area where survivors fled.

Meanwhile, in the northeastern Nigerian state of Borno, the Islamist terror group Boko Haram was believed to be responsible for an attack on a mosque in the city Maiduguri.

Authorities report at least 22 people were killed and 18 wounded when a female suicide bomber sneaked into the mosque during early morning prayers, detonating a bomb. Another bomber blew herself up outside the mosque as survivors were fleeing.

Boko Haram, whose name means “Western education is forbidden,” originated in Maiduguri and has been responsible for 20,000 deaths since 2009. Over two-million Nigerians have been internally displaced due to the group’s attacks.

A year ago, the group pledged allegiance to the Islamic State.

Watch: Boko Haram Is Deadlier Than ISIS. Why Don't We Care?