Riot police cordon the Coptic church that was bombed on Sunday in Tanta, Egypt April 9, 2017. REUTERS/Mohamed Abd El Ghany

CAIRO (Reuters) - Personnel assigned to the U.S. Mission in Egypt are prohibited from visiting religious sites outside greater Cairo until further notice, the U.S. embassy said on Monday in a security message posted on its website.

“Terrorists have attacked targets associated with the Christian community in Egypt. Incidents have occurred in both urban and isolated settings. Additional attacks may be possible,” the message said.

“Until further notice, personnel assigned to the U.S. Mission in Egypt are prohibited from visiting religious sites outside greater Cairo. U.S. citizens residing in or visiting Egypt should take prudent steps to enhance their personal security,” it said.

Gunmen attacked a group of Coptic Christians travelling to a monastery in central Egypt on May 26, killing at least 29 people and wounding 24. Many children were among the victims.

Islamic State took responsibility for the attack, which came on the eve of the Islamic holy month of Ramadan. It followed other church bombings claimed by the militant group in a campaign of violence against Christians.