An unidentified leader of Egypt's affiliate of the so-called "Islamic State" (IS) jihadist group warned in an interview Thursday that places where "crusader nationals of western countries" gather, including churches and government facilities, were all "legitimate targets" for future attacks.

"We warn you to stay away from gatherings and places of interests to Christians, army and police, political and economic government facilities as well as gatherings of nationals of the Western crusaders," the leader said in an interview published by the group's al-Nabaa newsletter.

Read more: 'Islamists set on wiping out Coptic Christians'

"This is an apostasy from Islam and they have to hurry up and repent," he said, adding that security campaigns against the group tend to "backfire," thereby having a "positive impact on the Mujahedeen."

The threat comes just days after Pope Francis led Mass for thousands of Catholics in Cairo as part of his historic visit to Muslim-majority Egypt.

Copts targeted by extremists

The Egyptian affiliate of 'IS' has claimed responsibility for last month's twin attacks on two of Egypt's Coptic Christian churches that killed more than 45 worshippers. In response, Egypt's government announced a three-month state of emergency.

Read more: The Copts: A Christian minority with a long history

Those attacks followed the bombing of a Christian cathedral in Cairo during a Sunday mass procession last December that killed more than two dozen people.

Copts, Egypt's largest Christian community, have repeatedly complained of discrimination and being the immediate targets of Islamist terror attacks.

Egypt's Christian minority, which accounts for around 10 percent of the country's population of 92 million, rallied behind general-turned-president Abdel-Fattah al-Sisi in 2013 when he ousted his predecessor Mohammed Morsi of the Muslim Brotherhood group.

Since then, however, attacks on Christian homes and businesses have surged, particularly in the Egypt's southern Sinai Peninsula. Faith in the Sisi regime appears to be quickly eroding.

Egyptian security forces in Sinai have meanwhile also suffered near-daily attacks perpetrated by an 'IS' branch based in the region.

dm/bw (AP, dpa)