At least a dozen people were killed in clashes between Muslim and Christians during a street protest in Cairo.

Thousands of Christians demonstrating against the burning of a church were attacked by Muslim mobs last night.

The clashes added to a sense of continuing chaos in Egypt after the 18-day democracy uprising that toppled leader Hosni Mubarak on February 11.

The uprising left a security vacuum when police pulled out from Cairo and several other cities three days into the uprising.

The police have yet to fully take back the streets, something that has left space for a wave of violent crime and lawlessness in some parts of the nation.

Muslims torched the church amid an escalation of tensions between the two religious groups over a love affair between a Muslim and a Christian that set off a violent feud between families of the couple.

The Christian protesters yesterday blocked a vital road, burning tyres and throwing stones at cars.

An angry crowd of Muslims set upon the Christians and the two sides fought battles with guns, knives and clubs for about four hours.

Mubarak handed power to the military when he stepped down, but the military does not have enough troops to police every street in Cairo, a sprawling city of 18 million people that, at the best of times, is chaotic.

Even before the uprising unleashed a torrent of discontent, tensions had been growing between Christians and Muslims.

On New Year's Day, a suicide bombing outside a Coptic church in Alexandria killed 21 people, setting off days of protests. Barely a week later, an off-duty policeman boarded a train and shot dead a 71-year-old Christian man, wounding his wife and four others.

Egypt's ruling generals pledged last week to rebuild the torched church and the country's new prime minister, Essam Sharaf, met the protesters to reassure them that his interim government would not discriminate against them.