Islamic State called on insurgents in Egypt's Sinai Peninsula on Monday to press ahead with attacks against Egyptian security forces and continue beheadings, an announcement likely to deepen concerns over ties between the militant groups."Rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads. Do not let them feel secure," IS spokesman Abu Muhammad al-Adnani said in a statement released online.He praised Egyptian militants for carrying out "blessed operations against the guards of the Jews, the soldiers of Sisi, the new Pharaoh of Egypt."Islamic State, fighting to redraw the map of the Middle East, has been coaching Egypt's most dangerous militant group, complicating efforts to stabilize the biggest Arab nation.Confirmation that Islamic State, currently the most successful of the region's jihadi groups, is extending its influence to Egypt will sound alarm bells in Cairo, where the authorities are already facing a security challenge from home-grown militants.A senior commander from the Sinai-based Ansar Bayt al-Maqdis, which has killed hundreds of members of the Egyptian security forces over the past year, said Islamic State has provided instructions on how to operate more effectively."They teach us how to carry out operations. We communicate through the internet," the commander, who asked to remain anonymous, told Reuters."They don't give us weapons or fighters. But they teach us how to create secret cells, consisting of five people. Only one person has contact with other cells."Militant groups and the Egyptian state are old foes. Some of al-Qaida's most notorious commanders, including its current leader Ayman al-Zawahri, are Egyptian.One Egyptian president after another has crushed militant groups but they have always resurfaced.The success of Islamic State in seizing large parts of Syria and Iraq has raised concerns in Egypt, where authorities are battling Ansar as well as militants who have capitalized on the chaos in post-Gaddafi Libya to set up over the border.Islamic State became the first jihadi group to defeat an Arab army in a major operation after steamrolling through northern Iraq in June almost unopposed by the Iraqi military.