In April, two Islamic State suicide bombers killed at least 45 people at churches in the cities of Alexandria and Tanta, one of the bloodiest attacks the country has experienced in years.
State of emergency in Egypt after Islamic State church bombings kill 44
"We are warning you to stay away from Christian gatherings, as well as the gatherings of the army and the police, and the areas that have political government facilities," the leader, who was not named, said in an interview in Islamic State's Al Naba weekly newspaper published on Telegram.
Militants are increasingly targeting religious minorities, a challenge to President Abdel Fattah al-Sisi, who has promised to protect them from extremism.
Islamic State has been turning its sights on targets outside its base in the Sinai, putting more pressure on the government and presenting extra challenges for security services.
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