THE leader of Nigeria's Christians warned at the weekend that deadly attacks on churches and the faithful suggested "religious cleansing", comparing the violence to the run-up to the 1960s civil war.

The upsurge in violence coincides with the government stopping fuel subsidies in Nigeria, effectively doubling prices overnight.

The stark warning in Africa's most populous nation and its largest oil producer follows at least six gun and bomb attacks on Christians since Christmas, killing more than 80.

Islamist group Boko Haram has claimed responsibility for most of the violence, which has sparked fear of a wider religious conflict in a country whose 160-million population is roughly evenly divided between a mainly Muslim north and a predominantly Christian south.

A week ago, a purported spokesman for Boko Haram gave southerners living in the north a three-day ultimatum to leave the region.

Under mounting pressure to act, President Goodluck Jonathan placed areas hard hit by attacks blamed on Boko Haram under a state of emergency on December 31, but the violence has only continued and spread to other locations.

In a televised address to the nation on Saturday evening devoted to a controversial policy that has seen fuel prices skyrocket, the president said the "mindless acts of violence . are unfortunate".

A number of the recent attacks, including in Mubi and the cities of Yola and Gombe, occurred in areas outside the emergency decree.

More than 30 Christians were gunned down in three separate attacks at the weekend.

At mass in the capital Abuja yesterday, worshippers were frisked and made to pass through metal detectors - measures that have been in place for several weeks.

Christian Association of Nigeria head Ayo Oritsejafor said after a meeting of church leaders on Saturday that Christians would defend themselves, though he said he was not advocating reprisal attacks.

Mr Oritsejafor said an emergency meeting of church heads concluded "that the pattern of these killings does suggest to us a systematic ethnic and religious cleansing".

"We are reminded, by the occurrences of these killings, of the genesis of the civil war that took place here in Nigeria," he said.

The run-up to Nigeria's 1967-70 bloody civil war, which left more than 1-million dead, saw overwhelmingly Christian Igbos massacred in the north. An attack on Friday in the northeastern town of Mubi was a frightening reminder for many of the days before the civil war, with 17 people gunned down as they gathered to mourn the death of an Igbo killed the night before.

Bombings on Christmas, particularly one that killed 44 people as services were ending at a Catholic church near Abuja, sparked intense fear and outrage.