The security source in the port city of Alexandria said there had been a blast outside a church at about midnight, but they did not have details on any dead or injured. 

The television channel cited witnesses who said the blast was caused by a car bomb and that ambulances were in attendance treating an unknown number of casualties. 

Muslim majority Egypt has a large Christian minority, making up about 10 percent of the nation's 79 million. 

In recent months, there have been clashes centred on religious differences. In November, a confrontation between hundreds of Christians and riot police in Cairo took a sectarian turn when dozens of Muslims became involved in the violence, lobbing rocks from behind a security cordon.