Some 22,000 people have sought shelter in police stations in the northern Nigerian city of Kano.
Christians are a small minority of Kano's population
They are mostly Christians from other parts of Nigeria, who fled from Muslim youths with knives and machetes.
The city is now calm but casualties are still arriving at hospitals. The Red Cross has confirmed 36 deaths.
Police have deployed in Lagos and other cities to prevent the spread of rioting - sparked when hundreds of Muslims were killed in central Nigeria.
AFP news agency reports that doctors at Kano General Hospital are refusing to allow anyone near the morgue for fear of inflaming the tense situation.
"We will wait until everything is calm until we give the bodies out or allow anybody to go in to check for his relations," a doctor told AFP.
'Excuse for violence'
According to the BBC's Anna Borzello in the mainly Muslim city of Kano, many described the attackers as unemployed youths who were using religion as an excuse to loot and cause mayhem.
Our correspondent saw one woman with a bandage tied around her wrist where she had been cut trying to protect her baby from attack.
Another man had a scar on his head, bloodstained trousers and knife marks sliced into his back.
"I saw them put an old tyre on his neck and set him ablaze," said a 30-year-old Christian, Barry Owoyemi, of a dead Christian neighbour.
Police commissioner Ganiyu Dawudu told our correspondent that he believed the fighting was over following Wednesday's clashes.
Armed police and soldiers are patrolling the city's streets.
They also turned out in the capital Lagos and northern cities in an attempt to keep the peace.
Earlier, Kano's Islamic leaders joined Nigeria's President Olusegun Obasanjo in urging calm.
President Olusegun Obasanjo on Thursday visited Yelwa, the central town where the crisis began when Christian militants killed hundreds of people.
Mr Obasanjo went on to visit a relief camp where 27,000
people who had fled Yelwa were staying.
He strongly rebuked Christian and Muslim leaders for not doing more to stop the violence, AFP reports.
"Did your own Christianity teach you about revenge?" he said after a Christian leader asked him why the authorities had not helped Christians attacked by Muslims two months ago.
During the tour, some clerics questioned Mr Obasanjo's commitment in bringing an end to inter-religious violence.
Others strongly criticised the length of time which elapsed before the president visited the trouble spots.
Reporters said Mr Obasanjo responded angrily, at one stage calling a local Christian leader "a total idiot".
Blessing Adaiyi's sister was killed in the violence
The president has been given a report into the Yelwa massacre but this has not been made public.
He has vowed to end the cycle of violence but did not say how.
The most recent rioting began after a demonstration to protest at the Yelwa killings, at which Mr Obasanjo was given a seven-day ultimatum to deal with the situation or face the consequences.
More than 10,000 people have been killed in ethnic, religious and political violence in the country since the end of military rule in 1999.
Nigeria's combined Christian and animist communities are roughly equal in size to its Muslim population, with the Christians living predominately in the south.