The military authorities in Egypt have said they will take strong action to protect national security after clashes between Muslims and Christians in Cairo left 12 people dead.

Ministers at an emergency cabinet meeting promised to use what they called 'an iron fist' to restore order.

More than 190 people detained after the clashes are to face military trials, in a move the ruling Supreme Council of the Armed Forces called a 'deterrent' against further violence.

'Gatherings around places of worship will be banned to protect their sanctity and ensure the security of residents and prevent sectarian strife,' Justice Minister Mohamed el-Guindy said in a statement read on state television.

The violence began after several hundred conservative Muslims gathered outside a Coptic Christian church in Cairo, protesting over an allegation that a Christian woman who wanted to convert to Islam was being held there against her will.

Sectarian strife often flares in Egypt over conversions, family disputes and the construction of churches.

Muslims and Christians made demonstrations of unity during the protests that overthrew Hosni Mubarak, but interfaith tensions have grown.