Egypt has asked Gaza’s Hamas rulers for information on three members of an Islamist group suspected of involvement in a deadly attack on a military outpost, a senior security official said on Saturday. He said Egyptian authorities had received a list of nine suspects from Israel, and asked the Palestinian Islamist movement Hamas to provide information on three of the men. They are believed to be affiliated with the Army of Islam, a small radical Islamist group which Egypt has blamed for several attacks in past years. The Egyptian military has been bolstering its presence in the Sinai with tanks and helicopters after Sunday’s unprecedented ambush on a border guard outpost near the borders of Gaza and Israel. It said the attack took place under the cover of mortar fire from Gaza, but witnesses told AFP they heard only rifle fire. The attackers commandeered a military vehicle into Israel but were killed in an Israeli helicopter strike. The military and state media said on Wednesday that it killed 20 militants out its first air strikes in Sinai since it regained the peninsula in a 1979 peace treaty with Israel. Residents in the villages where the airstrikes took place denied anyone had been killed.