The Egyptian authorities have arrested 13 suspected "terrorists" allegedly planning to attack Christians and public institutions, a week after deadly church bombings. <br/><br/>The Interior Ministry's announcement came as Egypt's Christians marked Easter under tight security, a week after Palm Sunday bombings claimed by the Islamic State group that killed 45 people at churches in the cities of Tanta and Alexandria.<br/>'<br/>The "13 terrorist elements" belonged to cells preparing attacks against "government and Christian institutions" and police in four northern provinces including Alexandria. ''<br/><br/>Parliament on Tuesday unanimously approved a three-month state of emergency declared by President Abdel Fattah al-Sisi in the aftermath of the attacks.<br/><br/>Copts, who make up about one tenth of Egypt's population of more than 92 million, have been targeted several times in recent months.''<br/>