At least 30 police officers in Nigeria have been killed in an ambush by a local militia in the central Nasarawa state, officials have said.
They were on their way to arrest the leader of the outlawed Ombatse “cult” when gunmen opened fire, a state spokesman told the BBC.
Sani Musa Mairiga said they were forcing local villagers to swear an oath of allegiance to the group.
The state police chief said that 17 officers were still missing.
One source at the hospital where the bodies were taken told the BBC dozens more policemen were killed in the attack.
Nigeria’s President Goodluck Jonathan has cut short his visit to South Africa and cancelled a state visit to Namibia to oversee the response to the latest violence.
Nasarawa police chief Abayomi Akeremale said about 60 police officers came under attack on Tuesday.
“We decided to send our men to the area to arrest members of Ombatse, including their priest,” he told the AFP news agency.
“[They] have been going to churches and mosques initiating people into their cult by forcefully administering an allegiance oath to unwilling people.”
The police were attacked near the shrine to the traditional deity of the Eggon people, in the village of Alakyo, near the state capital, Lafia.
The ambush came after 55 people were reportedly killed in the north-east of Nigeria in co-ordinated attacks by the Boko Haram Islamist militant group.
The Nigerian army said 105 prisoners were freed in Tuesday’s pre-dawn raid in Bama, Borno state.
Bama’s police station, military barracks and government buildings were burned to the ground, said the military and witnesses.
A statement from the president’s office said Mr Jonathan was returning to Abuja “to personally oversee efforts by national security agencies to contain the fresh challenges to national security which have emerged this week in Borno, Plateau and Nasarawa States”.
Oh his arrival back in Nigeria, Mr Jonathan is set to head a meeting reviewing Nigeria’s security situation with the country’s military and police chiefs.
The Ombatse, which means “the time has come” in the Eggon language, say they are fighting against social vices such as alcohol and adultery.
The Eggon community are a microcosm of Nigeria – they are said to be evenly divided between Christians and Muslims but many people continue to follow traditional religions.
There are about 250 different ethnic groups in Nigeria, some with their own traditional belief systems.