"Members of the al-Qaida-linked group Army of Islam hid behind elements they recruited," Egyptian Interior Minister Habib al-Adly said during a televised speech marking National Police day.
The interior minister said there was "conclusive evidence of their (Army of Islam) involvement in the sordid planning and implementation of this mean act of terrorism on Egyptian land, where many others died defending the Palestinian cause," the Chinese news agency Xinhua reported Sunday.
A source in Gaza denied involvement in the church bombing, the agency said.
A suicide bomber detonated a nail-packed bomb outside the Two Saints Church in Alexandria shortly after midnight Jan. 1, killing 23 people and injuring up to 100.
The Army of Islam was involved in the abduction of British journalist Alan Johnston three years ago. He was held captive in Gaza for three months. The group was also tied to the abduction of Israeli soldier Gilad Shalit in June 2006.