A car bomb exploded outside a church in Egypt's northern city of Alexandria at midnight, killing 21 people and severely injuring many others, including 8 Muslims, among whom were the police officer and three men guarding the church, security sources told Ahram online on Saturday. Initial reports had put the number of killed at 8 and injured at 24, but have since been adjusted as authorities were able to gain more information on the effects of the bombing.

The blast went off about a half-hour after midnight as worshippers were emerging from a New Year's Mass at the Saints Church in Sidi Bishr, Alexandria. The blast came from a car parked outside the church. Police sources said it was a green car, with newly issued licence plates, but gave no further inofrmation.

So fierce was the explosion that it damaged the church building and that of the Shark Al-Madina Mosque across the street. According to eyewitnesses, the torn body parts of the victims were spread over a wide area of the street.

After the explosion, the outraged members of the congregation errupted in demonstration, which continued into the early hours of Saturday morning. Some of them, reportedly, made a brief attack on the mosque across the street, but were stopped by the police.

The demonstrators hoisted a cross and a large white sheet which they bloodied with the blood of the victims, whom they declared martyrs. They also held a mass for the vicitms souls.

Police said they excercised restraint in dealing with the demonstrators in understanding for their anger and sense of outrage.

The Saints Church came under attack before when a man with a knife stabbed worshippers in April 2006.

The attack comes at a time of heightened sectarian tensions in the region, when al-Qaida-linked militants have carried out a campaign of attacks against Christians in Iraq, killing 68 in a church siege in October and two more Christians in attacks in Baghdad on Thursday.

The attacks in Iraq have an unusual connection to Egypt. Al-Qaida in Iraq says it is carrying out the campaign of anti-Christian attacks in the name of two Egyptian Christian women who reportedly converted to Islam in order to get divorces from their husbands.

The two women have since been secluded with Coptic Church authorities. Islamic hard-liners in Egypt have held frequent protests in past months, accusing the Church of imprisoning the women and forcing them to renounce Islam and return to Christianity. Al-Qaida in Iraq says it is carrying out attacks on Christians in that country until Egyptian Church officials release the two women. The Church denies holding the women against their will.

Christians are believed to make up about 10 percent of Egypt's population of nearly 80 million people, and the country has seen increasing sectarian tensions. In January 2009, seven Christians were killed in a drive-by shooting on a church in southern Egypt during celebrations for the Orthodox Coptic Christmas, but bombings against churches have been rare in recent years