Egypt's interior minister has blamed a Palestinian group linked to al-Qaida for the New Year's Day suicide bombing that killed more than 20 people and wounded about 100 others at a Coptic Christian church.
Habib al-Adly announced Sunday that the government believes the Army of Islam was behind the attack.
The Army of Islam denied any involvement in a swift response to the allegations.
The New Year's Day attack occurred at a church in the northern city of Alexandria where worshippers had gathered to celebrate Mass.
The bombing prompted protests by Christians saying the state had not done enough to protect them from extremists. Witnesses also said that after the attack, Coptic Christians tried to attack a mosque across from the church, and that fights broke out causing more casualties.
The Palestinian militant group Hamas condemned the attack, saying the perpetrators were seeking to promote confrontation between Muslims and Christians.
Tensions between Christians and Muslims have been on the rise in Egypt and Iraq following threats by al-Qaida.
While no one immediately claimed responsibility for the New Year's Day attack, al-Qaida's affiliate in Iraq had called for attacks on Egypt's Coptic Christians.