Sporadic outbreaks of ethnic and religious violence are not new to Kano, but a radical group of zealots known as the Muslim Brothers is gaining ground among the youth of the dominant Hausa people by spreading the message of Tajdid, or Islamic renewal.
"Here in the north of Nigeria there has been a simmering feeling that Muslims are being relegated to the background, and that Islam is being stampeded out of existence," said Suleimanu Kumo, a lawyer and member of a government-appointed "inter-ethnic peace committee". "They are feeling marginalised. You find it especially among the youth."
Tension between young Hausa Muslims and Christian Igbo from eastern Nigeria, who dominate the city's petty trading sector, has always been near the surface. It erupted in its most violent form in the ethnic massacres that preceded the 1967-70 civil war. Widespread riots in October 1991 left several hundred dead and saw churches and mosques burned to the ground.
But the murder and beheading last December of Gideon Akaluka, a young Igbo trader who allegedly desecrated the Koran, and a new outbreak of riots in May have kept the city of three million people on a knife edge.
Akaluka was arrested in December after his wife allegedly used pages of the Koran as toilet paper for her baby. After he was imprisoned by the police, a group of Muslims broke into the jail, killed him, and walked around the city parading his severed head.
But Akaluka's lawyer said he had obtained affidavits which proved that his client was not at the compound at the time and that the woman allegedly guilty of the offence was not his wife. No one has been arrested for Akaluka's murder.
A former presidential candidate, Maitama Sule, said if tension were not reduced "we may end up with a revolution which is just not religious, but may be political, social and economic. Symptoms of revolt loom large on the horizon today. It is a group of disgruntled elements who are out to vent their anger who are joined by some irresponsible, undesirable waste products of humanity."
The history of Kano is rich in Islam. Ali Yajib Tsamia was one of the first rulers to convert, in the 14th century. But his was largely a palace religion, with the great mass of people, even those living inside the city walls, 12 miles of thick embankments 30ft to 50ft high, left untouched by the teachings of the Koran. By the closing decades of the 15th century, all the major rulers in the Sahelian belt were Muslims and some had contacts with North African and Egyptian scholars.
When the Muslim scholar Usman dan Fodio launched the Islamic Jihad in the 19th century, Kano was incorporated into the Sokoto Caliphate which ruled north-western Nigeria until Frederick Lugard conquered the region with his West African Frontier Force in 1903. Since Nigeria's independence from Britain in 1960, the state was declared secular, and Christianity has been making inroads into the north.
"Religiously, or spiritually, the Muslims now feel that the battle has been brought to their domain, especially in areas like Kano, which seemed to be the last bastions," said Matthew Kukah, a Catholic priest and author of Religion, Politics and Power in Northern Nigeria.
The main focus of concern now are the Muslim Brothers, a group of men who broke away from their erstwhile mentor, the pro-Iranian preacher Ibrahim Zakzakhy. "They are men, 17, 18, up to 28 years old, and they are people who have nothing to lose, who have life rather more than death to fear," said Mr Kumo.
After initially agreeing to hold discussions with the inter-ethnic peace committee, the Brothers have gone underground. They allege that four of their members were executed on 22 June by the military government.
The Brothers' message is that Christianity is being favoured by the military government and that traditional leaders such as the emirs have forfeited their role as the champions of Islam. "The military undertook not only to give them fat salaries; they built very beautiful palaces for them, gave them fat contracts, and they in fact keep on dishing out large amounts of money to them," said Abdullahi Mahadi, Director of the Ahmadu Bello University Centre for Research and Historical Documentation in Kaduna.
"It is the suspicion that Christianity could change the whole religious landscape of this place that has been consciously or unconsciously has been responsible for the repeated religious crises we have had," said Father Joseph Bagobiri of the Roman Catholic Kano Independent Mission.
Mr Sule, the chairman of the peace committee, said Muslims might have as much to fear as Christians from the new radicalism. "The fear is that if this thing is allowed to go on without check, it may be the non-Muslims tomorrow, the next day it may be a section of the Muslims."
Anger over Nigeria's economic collapse, the result of instability, rampant corruption and mismanagement by 12 years of military rule, runs deep in Kano. "Whenever you find people not properly employed, there is no other way to express yourself, because you have the police, and the emirs and their agents looking for troublemakers," said Professor Mahadi. "So the most important thing is to express this in Islam."
Observers from both sides of the ethnic and religious divide blame Nigeria's military authorities for worsening the crisis. "The military have always played this card very well," said Fr Bagobiri. "Because the whole thing started during the [Ibrahim] Babangida regime. That was when the religious divide became very strong."
The government's disastrous handling of the Akaluka affair is a case in point. Mr Sule, normally a defender of General Sani Abacha's military regime, describing it as "experienced and responsible", was outraged by the incident. "I can't understand how in a society where we have a government, the police and judiciary, that a group of people take the law into their hands, go to the prison, break into the prison, and get somebody out of his cell, cut off his head, and take the head around the next day with impunity."
Observers like Father Kukah see the sinister hand of the military and the northern elite behind the trouble. "Let's be clear: there are Nigerians who have invested heavily in violence, in ignorance, in poverty, in turbulence. Because it is when you now have this anarchic situation, that they present themselves as the praetorian guard."