Nigeria is to launch a major security operation after a wave of retaliatory violence between Christians and Muslims claimed as many as 169 lives in the centre of the country.

A curfew was declared in Plateau State in an attempt to end one of the deadliest episodes of an increasingly bloody conflict between Muslim cattle herders and Christian farmers that has swept large parts of Africa’s most populous country.

With fears mounting that Nigeria is slipping into an inter-communal war, Muhammadu Buhari, the country’s president, condemned the latest bloodshed as “deeply unfortunate.”

His police chief, Ibrahim Idris, announced the deployment of a special force in Plateau.

“The intervention is to put an end to the violence,” he said.

Police officials said the latest round of clashes erupted on Thursday when Christian farmers from Plateau’s native Berom tribe killed five Muslim Fulani cattle herders they accused of trespassing on their land.

The Fulani, who mainly come from northern Nigeria, retaliated with a wave of attacks on six villages in the Barkin Ladi region of Plateau State. In one incident, the two young children of a clergyman were hacked to death, according to a local Christian rights group.

Officials in the state put the death toll at 120, while some activists said that 169 had died. Nigeria’s police, frequently accused of understating death tolls, said 86 people were killed.