Sixteen people died yesterday when Nigerian Muslims protesting against cartoons of the Prophet Mohammad torched 11 churches and rioted in the north of the country, police said.
It was the deadliest outbreak of violence so far in demonstrations which have swept the world over the cartoons, and the first violent protest in Nigeria, whose 140 million people are divided about equally between Christians and Muslims.
Police spokesman Haz Iwendi said 15 people were killed by rioters in the northeastern state of Borno where the churches were burned, and one person died in similar riots in the north-central state of Katsina.
"The army is assisting the police and a curfew has been imposed," Mr Iwendi said in reference to the Borno riot. Police arrested 115 people in the Borno state capital Maiduguri and 105 in Katsina, he added.
Several hotels, shops and vehicles were also torched in Maiduguri by the demonstrators who ran wild after police fired teargas to disperse them, residents said.
Joseph Hayab, north-west secretary of the Christian Association of Nigeria, told Reutersmost of those who died were Christians.
"The Muslim group came out to protest and the security forces tried to ensure it was peaceful, but there were some hoodlums in the crowd and somehow the security forces shot one or two of them," he said.
"They went on the rampage, burning shops and churches of the Christians. The protesters killed the others. Some were even killed in the churches."
The state government said troops were deployed in the streets of the capital to restore order. In previous religious riots in Nigeria the army has been given a shoot-to kill order to restore calm.
The far northeastern state on the edge of Lake Chad is predominantly Muslim with a sizeable Christian population. The state has recently seen an increase in Islamic radicalism.
Thousands have been killed in Christian-Muslim clashes over the last five years in Nigeria. Twelve northern states, including Borno, introduced Islamic sharia law in 2000 which has contributed to the animosity between the two religions.
Last week, assembly members in the northwestern state of Kano burned Danish flags in protest at the publication of the cartoons and said they would impose a boycott of Danish goods.
The satirical cartoons were first published in a Danish newspaper last year and reprinted in European newspapers this year, triggering protests across the Muslim world.