CAIRO (Reuters) - Angry Coptic Christians clashed with police on Sunday as they demanded more protection for Egypt's Christians following a New Year's Day church bombing that killed 21 of their brethren.
Hundreds of members of Egypt's large Christian minority protested in Cairo and Alexandria, the northern city where the presumed suicide bomber detonated a device outside a church during a midnight service.
A security source said Egypt was holding seven people for questioning over Saturday's bombing, which also wounded 97 people, and had released 10 others.
At Saint Mark's Cathedral, the Cairo base of Orthodox Pope Shenouda, several hundred young Copts fought police on Sunday as they tried to leave the cathedral grounds and take to the streets to demand more protection for Christians.
Their protest continued into the night, the crowd held back by a cordon of riot police nine men deep. A church official approached the crowd briefly to try to calm them down, without success.
"Security - are you with us or with them?" the men cried. "You government are cowards."
"Pope Shenouda, have a care. We are youth. We will protect you with our blood," the men shouted, many of them holding aloft makeshift wooden crosses. "Revolution, revolution in Egypt, in all churches of Egypt."
Earlier, protestors in Cairo had heckled government officials who visited the cathedral compound to offer condolences: "Where are you, Interior Minister, when they are killing our brothers before your eyes?"
Some protesters pelted a minister's car with stones when he left, witnesses said. Some visiting Christian officials had cars shaken by angry demonstrators, while other protesters scuffled with police outside the compound.
Extra police officers were posted outside several churches in Cairo and Alexandria on Sunday, preventing cars from parking next to the buildings, witnesses said.
Pope Benedict, head of the Roman Catholic church, condemned the bombing as a "vile gesture," the latest in a series of attacks on Christians in the Middle East and Africa.
Egyptian officials said there were indications that "foreign elements" were behind the blast and that it seemed to have been the work of a suicide bomber.
An Iraqi group linked to al Qaeda threatened in November to attack Egypt's Coptic Church. And about two weeks before the bombing, a statement on an Islamist website urged Muslims to attack churches in Egypt and elsewhere around Christmas, which for Orthodox denominations such as the Copts falls on January 7.
A statement on another Islamist website after the blast read: "This is the first drop of heavy rain, hand over our prisoners and turn to Islam." No group was named.
Islamist groups have accused the Church of trying to coerce Christian women who wanted to convert to Islam.
One protester, Nader Shenouda, said: "When there was a threat from al Qaeda a month or a month and a half ago, did the government have to wait till the disaster happened before protecting us?"
Sheikh Ahmed El-Tayeb, the head of al Azhar, Egypt's most prestigious seat of Sunni learning, visited the Muslim Orthodox Coptic Pope Shenouda to express condolences.
President Hosni Mubarak, 82, has pledged to track down the culprit. He made a televised address on Sunday calling for national unity, saying the attack was directed at all Egyptians, not just Christians.
Christians make up about 10 percent of Egypt's 79 million people. Tensions often flare with the majority Muslims over issues such as building churches or close relationships between members of the two faiths.
Analysts said the attack was on a much bigger scale than typical sectarian flare-ups but said laws that make it easier to build a mosque than a church, and similar causes of Christian complaint, meant such an attack would fuel sectarian tension.
Angus Blair, head of research at investment bank Beltone Financial, said the blast was likely to be brushed off by investors in the bourse and was not likely to have a "material negative impact" on tourism, a major revenue source.