The Islamic State (IS) group has claimed responsibility for a suicide bombing at a Cairo church that killed 25 people over the weekend.
In an online statement on December 13, it said the bomber had killed and injured 80 people, and vowed "to continue war against apostates."
President Abdel-Fattah el-Sissi has identified the bomber as Mahmoud Shafiq Mohammed Mustafa, 22.
IS called the bomber by a nom de guerre, Abu Abdullah al-Masri.
The attack, which killed mainly women, was among the deadliest in recent memory to target Egypt's Coptic minority, which makes up around 10 percent of the population and was largely supportive of the military overthrow of a freely elected Islamist president in 2013.
Sissi led the ouster of President Mohammed Morsi, a senior figure in the now-outlawed Muslim Brotherhood group.
Since then, Islamic militants have carried out scores of attacks, mainly targeting security forces, while the government has waged a wide-scale crackdown on dissent.
Small protests were held outside the church in the aftermath of the attack, as Christians accused the government of failing to protect them.
Three men and a woman were arrested in connection with the bombing.