TEL AVIV, Israel — A senior Israeli military official says the air force has deployed a special unit of unmanned surveillance aircraft along its long, porous border with Egypt after militants crossed the frontier and killed eight Israelis last month.

The official says the drones are monitoring both sides of the 150-mile (250-kilometer) border, though the aircraft are flying only in Israeli airspace. In the wake of the attack, Israel also has sent more troops along the border.

Officials have grown increasingly concerned about the security situation in Egypt's Sinai Peninsula following the ouster of longtime Egyptian President Hosni Mubarak in February.

The official spoke on condition of anonymity under military guidelines.

Israel, along with the United States, is a world leader in drone technology.