Egyptian Interior Minister Habib al-Adly said on Sunday that a Palestinian group was behind the New Year's church attack in the Mediterranean city of Alexandria that killed 21 people.
"If elements of the Palestinian Army of Islam, linked to al-Qaeda, thought they had hidden behind elements that were recruited, we have decisive proof of their heinous involvement in planning and carrying out such a villainous terrorist act," Adly said in a speech to mark Police Day, carried live on state television.
The announcement was made in a ceremony attended by President Hosni Mubarak, senior cabinet ministers and top police officials.
Mubarak praised the police for finding out who was responsible for the bombing and said the attackers had "tried to sow discord between Copts and Muslims".
A suicide bomber blew himself up outside the church in the Mediterranean city as worshippers emerged from a New Year's Eve mass. The official MENA news agency puts the death toll at 23, with scores more wounded. Previously, the death toll stood at 21.
Security officials said an unspecified number of people have been detained in connection with the bombing but gave no more details. They spoke on condition of anonymity because they were not authorized to share the information with the media.
No one has claimed responsibility for the attack, which followed threats to Egypt's Copts from the al-Qaeda-linked group in Iraq that claimed an October 31 attack on a Baghdad church.
Egypt's Christians, who make up 10 percent of the 80-million population, have been the target of several attacks and have repeatedly accused the authorities of systematic discrimination.
The Army of Islam played a part in a cross-border attack in 2006 in the Gaza Strip in which Israeli soldier Gilad Shalit was abducted. The group later cut relations with Hamas, the group which controls Gaza, and has clashed with Hamas.