Egypt on Sunday accused a Palestinian militant group, the Army of Islam, of carrying out a deadly New Year's Day church bombing with the help of a local accomplice.
Twenty-three people were killed in the blast outside a church in Alexandria, which prompted protests by Christians that the state had not done enough to protect them.
"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," Interior Minister Habib el-Adli said in a speech.
A spokesman for the Army of Islam, which considers al Qaeda's leaders as spiritual mentors, told Reuters in Gaza that the group "has no connection to the church attack in Egypt, though we praise those who did it".
The Islamist group Hamas, which controls Gaza, called on Egypt to share its evidence, saying that Israel was the only target of Palestinian armed groups.
In a statement, the Egyptian interior ministry said the Army of Islam had "relied on an Egyptian element" in planning the attack, and named the alleged accomplice.
"Ahmed Lotfi Ibrahim Mohammed was arrested and confessed he was tasked in 2010 to monitor Christian and Jewish places of worship and that he sent pictures of the Qideseen church in Alexandria to the Army of Islam" the ministry said.
It said the 26-year-old had confessed he had visited Gaza several times and was involved in planning the attack.
Egyptian officials had previously suggested that al Qaeda had a hand in the blast that ripped through a crowd outside the church. An Iraq-based al Qaeda group had called before the bombing for attacks on Egypt's Coptic Christians, who make up one tenth of the population.
The bomber died in the attack, which wounded 97 people.
Hamas rejected the idea of links between al Qaeda and Gaza militants and demanded Egypt provide evidence to back its claim.
"We confirm that there is no presence of the al Qaeda organisation in the Gaza Strip and that all Palestinian factions and groups point their rifles against the Zionist enemy and only against the Zionist enemy," Hamas spokesman Taher al-Nono said.
Hamas instead blamed Israel's foreign intelligence service Mossad for the Alexandria attack, without providing evidence.
President Hosni Mubarak, in an address broadcast on state TV, praised the police for their efforts to identify those responsible and said the attackers had sought to sow discord between Egyptian Copts and Muslims.
Sectarian tensions often flare in Egypt over issues such as building churches, religious conversions or romantic relationships between members of both faiths.
"We will not allow terrorism to shake our stability and horrify our people or attack the unity of Muslims and Copts," Mubarak said. "Egypt's security and stability are targeted."
Egyptian state security had pointed to possible foreign involvement and had investigated several Palestinians who it perceived as threats.
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 the Hamas government in Gaza and has clashed with it.
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