CAIRO - Egypt's Christians packed churches Thursday for mournful Christmas Eve Masses, weeping and donning black in place of colourful holiday clothes, under a heavy security cordon by police, fearing another attack like the New Year's suicide bombing of a church that killed 21 people.

At church gates around Cairo, police and church staff checked the IDs of those entering -- and their wrists, where many Egyptian Christians bear the tattoo of a cross.

Al-Qaida in Iraq had threatened Christians in Iraq and Egypt in the weeks leading up to the holidays and Saturday's deadly bombing. Militant websites have even posted names and addresses of churches in Egypt to target, raising fears of a follow-up attack on celebrations of the Orthodox Christmas, which Egypt's Coptic Christian minority marks on Friday.

The beefed-up police presence also appeared aimed at addressing Christians' fury over what they say is the government's failure to protect them and its ignoring of anti-Christian sentiment among Egypt's Muslim majority. The bombing sparked days of fierce clashes between Copts and police.

In that vein, state TV gave heavy coverage to the Christmas Eve Mass to promote a sense of unity. As it has in past years, the service at Cairo's Coptic Cathedral, the seat of the Church, was being broadcast live, along with Pope Shenouda III's sermon.

But this year, the ceremony was preceded by a live discussion by a team of prominent TV hosts and newscasters, all dressed in black, standing on the cathedral steps and speaking of the bonds between Muslims and Christians. A tiny logo of an intersecting cross and crescent was set in the corner of the screen. Christmas was declared a national holiday several years ago, in a nod by the government to inclusiveness.

"Today, I don't say I'm Muslim or I'm Christian," one of hosts pronounced. "I say, I'm Egyptian."

Muslims attended services at some churches around Cairo as a show of solidarity, getting permission from church officials ahead of time to get through police limiting access to Christians. "I wanted to do anything," said Hanan Mahfouz, a young woman in a Muslim headscarf holding a candle during a Mass in a church in the Cairo suburb of Maadi. "Coming here seemed like the least I could do."

But healing was hard to come by. Many Christians see the attack as proof of anti-Christian hatreds among Muslims and they day the state does little to address the sentiment despite the professions of unity repeated after any instance of violence.

"Some Muslims are good people," said Raymonda Ramzy, a 45-year-old worshipper dressed in black entering Mass at the main Coptic Church in the Cairo district of Giza. "But even on my way here, a couple of young men shouted at me, 'God take you all and rid us of you."'

While some Christians worried about attending services for fear of attack, she said, "I never hesitated. I wish I could die in church."

Egypt's Coptic Christian minority makes up 10 per cent of Egypt's 80 million people but complains of widespread discrimination they say relegates them to second-class citizen status. There has been growing anti-Christian violence in past years, mostly shootings or clashes between Christians and Muslims in villages.

Saturday's bombing was the deadliest in a decade -- and was qualitatively different, the first ever such suicide bombing targeting Christians, raising concern that al-Qaida may have a role, though investigators suspect a homegrown group likely carried it out. The blast hit a crowd of worshippers leaving a midnight Mass at the Saints Church in the Mediterranean city of Alexandria, killing 21 and wounding nearly 100.

In the southern province of Minya, a worker at a church on Thursday found a small explosive device packed with nails and fireworks planted under the building's stairs, a security official said, speaking on condition of anonymity because he was not authorized to brief the media. He said the device appeared to have been put there to "test security measures."

At the Saints Church in Alexandria, a double line of riot police stood at each end of the street. A stream of black-clad worshippers flowed in and bells rang as Mass began. Blood splatters remained on some of the walls inside. Police or church staffers asked those entering to show either a cross tattoo or an ID, which denote religion, to prove they were Christian.

Around two dozen Muslims held a solidarity gathering a street away from the Saints Church -- kept back by police. They held signs reading "no to terrorism, yes to citizenship" and "long live the cross and the crescent."

Across the country, police were preventing vehicles from parking near churches. The Interior Ministry asked church officials to prevent crowds from gathering in front of churches after Mass -- apparently to avoid providing a large target for attack, but perhaps also to avoid a new outbreak of protests. At the Cairo cathedral, security officers with walkie-talkies fanned out across the streets surrounding the cathedral, and metal detectors were set up at the entrances.

Turnout at churches appeared heavy, but at many of the normally festive services, a sombre mood reigned. At the main Giza church, no flowers or red carpet were laid out at the entrance as they usually are for the holiday, and women and children who would normally be decked out in festive holiday colours wore black.

The front pew at a church in the Cairo district of Omraniya was filled with prominent Muslims from the neighbourhood. Women in Islamic headscarves sat near Christian women in the headcoverings they don in church. Many women sobbed heavily during the service. Omraniya was the scene of fierce Christian riots in November that left two dead, sparked when police stopped construction work at the church.

"This is the way our Egypt climbs new heights and become prosperous," Father Hanna said in his sermon of the Muslims' presence. "We thank our brethren who came to share with us the joy of our feast, and the pain we feel over."

But many Copts remained deeply bitter and skeptical that the bloody attack would really bring change.

"It's worse than before," said Marina Sammy, a young woman at the Saints Church whose family owns a store in Alexandria. "The events haven't improved attitudes at all. We've been attacked and insulted and our store windows were broken. There's no security at all."

Diana Maher, at the Giza church, acknowledged the attempts to heal the rifts. But she said her own feelings toward Muslims had become stained with resentment and suspicion.

"At work, my Muslim colleagues and I say hello," she said. "But the first day back after the attack, I avoided them."