The authorities said that a suicide bomber blew himself up outside Al-Qiddissin church in the Mediterranean city of Alexandria early on New Year's Day, killing 21 people and wounding 79 others.
Protests by Christians and clashes with the police that erupted after yesterday's attack could worsen and plunge Egypt into a new spiral of sectarian violence, the government and independent newspapers said.
The papers also urged the government to give serious consideration to the plight of the Copts who account for up to 10 per cent of Egypt's 80-million population and often complain of discrimination.
"Someone wants to make this country explode...We must realise that there is a plot aimed at triggering religious civil war," the pro-government daily Rose el-Yussef said.
Egyptians should foil attempts by "terrorists" to strike at the country, it said.
The independent paper Al-Shorouk said Christians had a right to be angry, but urged them not play into the game of "the instigators of (Saturday's) crime."
"No one can blame the Christian brothers if they are angry and disgusted," the daily said.
The bombing sparked anger among Christians, who clashed yesterday for several hours with police and shouted slogans against the regime of President Hosni Mubarak.
"O Mubarak, the heart of the Copts is on fire," protesters shouted as they darted in and out of side-streets around the bloodied church to shower police with stones. Police fired tear gas grenades at the demonstrators.
Al-Shorouk said it would be "more dangerous for the Christians to be mired in their feelings of anger and frustration, than the attack itself."
"It would increase their isolation and the instigators of the crime would have then achieved their goal," it said.
"If all goes as planned, criminal operations against Coptic targets and holy places will increase. Copts will clash with their Muslim neighbours and we will be stuck in marshlands like Lebanon was in April 1975," it said.
A civil war broke out in Lebanon that month, lasting 15 years and pitting Christians against Muslims.
Another independent daily, Al-Masri Al-Yom, urged the authorities to take the bull by the horns and look beyond the security implications of yesterday's bombing, including at the political, social and cultural aspects.