Egypt's prime minister has appealed for calm after at least 24 people were killed and more than 200 wounded in some of the worst violence since an uprising ousted President Hosni Mubarak in February.

Prime Minister Essam Sharaf, in a televised address, said the violence threatened to throw off course Egypt's post-Mubarak transition to a democratic state.

A curfew was imposed overnight in central Cairo and the government held an emergency meeting early today to discuss the unrest.

The violence on October 9 pitted Coptic Christians, protesting against an attack on a church, against hard-line Muslims and Egyptian security forces.  

Rocks and petrol bombs were thrown and cars were set alight as the violence later spread from the city's TV center to Tahrir Square.  

An armored security van was reported to have struck several protesters.

Tensions between Christians and Muslims have increased since the February uprising.

Christians -- who make up about 10 percent of Egypt's 80 million people -- blame the country's ruling military council for being too lenient on those behind a spate of anti-Christian attacks since Mubarak's ouster.