|Coptic churches across Egypt are on high security alert ahead of Christmas celebrations [AFP]
Egyptian authorities have put up a heavy security cordon around the main Coptic cathedral in Cairo as worshippers attend a Christmas Eve Mass, in attempts to prevent another attack like the New Year's Eve suicide bombing at a church in Alexandria that killed more than 20 people.
Other churches across the country are on high alert for Thursday's celebration following the attack that sparked angry protests by Christians demanding more protection from the state.
Al Jazeera's Rawyah Rageh, reporting from Cairo, said many streets were blocked, with canine units, bomb detectors, and dozens of police officials personally supervising security.
Al-Qaeda in Iraq has been threatening Christians in Iraq and Egypt, while some websites have carried lists of names and addresses of churches in Egypt to target.
Coptic Christians celebrate Christmas on Thursday night and Friday.
Solidarity amidst tensions
In response to threats against the Copts, Egyptian activists have called on Muslims to form human shields in front of churches on Christmas Eve.
But Al Jazeera's Zeina Khodr, reporting from Alexandria, said that Muslims had been urged by the church not to attend the Christmas Eve Mass.
"The Coptic church here in Alexandria issued a statement yesterday asking Muslims not to attend the Christmas Eve Mass," she said.
"According to that statement they said that they have to take into consideration the feelings and the sensitivities of the relatives of the victims."
Khodr said there was a sense of defiance among the country's Christian population, who would not be frightened away and would continue to pray in churches.
There is also tension and a sense of anger, our correspondent said.
"The Christian community is angry; their anger directed at the state," she said.
Speaking to the Reuters news agency, Emad Atef, 25, a Christian who is a carpenter, said: "I no longer want to stay in this country.
"I am getting the paperwork to leave. I don't feel safe and neither do those around me."
Human rights groups say Egyptian police have been too slow to punish violence motivated by religion, sending a message that it is unacceptable.
Egypt's Muslims and Christians have co-existed for centuries, with occasional clashes often the result of family or business disputes or cross-faith relationships, rather than ideology.
Christians complain of discrimination in the job market and a lack of representation in government, the army and business.
A perception of growing intolerance is leading some to shun their Muslim compatriots.
Some blame growing tensions on a gradual Islamisation of education promoting a single, Islamic version of Egypt's identity that belies a diverse cultural history.
"Our school books are preaching Islamisation," said Youssef Sidhom, the Christian editor of weekly newspaper Watani.
"Coptic history of Egypt is to a vast extent withdrawn ... The syllabus is using Islam as the source of all traditions and norms."
Some young Copts, usually fiercely loyal to their church leaders, have begun to criticise them for keeping too low a profile and allowing political Islam to influence state policy.
Hosni Mubarak, the Egyptian president, has called for unity after the Alexandria attack, saying the bomber targeted all Egyptians.
The church bombed on New Year's Eve was previously targeted in 2006 when a man assaulted worshippers at two churches during Mass, killing one person and wounding five.
A year later, Christian shops in the area were attacked during the Muslim Eid al-Adha holiday after rumours spread of a love affair between a Muslim woman and Christian man.
One year ago, six Copts and a Muslim policeman were killed in a drive-by shooting outside a church after midnight Mass.