IAF warplanes flew over the Lebanese capital Beirut on Friday, a day after an attack by a Palestinian gunman killed eight Jewish seminary students in Jerusalem, raising tensions in the volatile region. "Two Israeli warplanes violated Lebanese airspace and flew over Beirut briefly before leaving the area," a senior Lebanese security official said. Speaking on condition of anonymity because he was not authorized to give official statements, he said the planes flew at a "medium altitude." The official did not elaborate and the Israeli army said it knows of no activity in Beirut. Three Israeli reconnaissance planes violated Lebanese airspace in southern Lebanon Thursday, the Lebanese army said in a statement Friday. The latest Israeli overflights come amid tensions over Thursday's attack in Jerusalem at the rabbinical seminary. Hezbollah's Al-Manar satellite TV station said a previously unknown group called the Martyrs of Imad Mughniyeh and Gaza was responsible for the attack - a claim that could not immediately be verified. Mughniyeh, a senior Hezbollah commander, was killed in a car bomb in Syria last month. Hezbollah has blamed Israel for the assassination and vowed retaliation.