Clashes have erupted outside government offices in the Lebanese capital Beirut after thousands attended the funeral of security chief Wissam al-Hassan who was killed by a car bomb on Friday.A group of protesters tried to storm the HQ, after a new call for Prime Minister Najib Mikat to resign. Police fired warning shots and tear gas.Friday’s attack also killed one of Mr Hassan’s bodyguards and a woman nearby.Opposition figures have blamed neighbouring Syria for the attack.Many have protested against Syria and its Lebanese allies amid fears the Syrian conflict could spill over.The confrontation outside the prime minister’s office lasted for a few minutes.Two former prime ministers Saad Hariri and Fouad Siniora intervened to urge their supporters to remain calm.Lebanon’s religious communities are divided between those who support the Syrian government - including many Shias - and those mostly from the Sunni community who back the rebels.Lebanon’s Shia militant group Hezbollah - a close ally of the Syrian government - condemned the bombing.Syrian Information Minister Omran al-Zoubi called it a "cowardly, terrorist act”. He said such incidents were "unjustifiable wherever they occur”.Syrian troops withdrew from Lebanon in 2005 after a 29-year-long presence, in the wake of the assassination of former Prime Minister Rafik Hariri.Mr Hassan, 47, was close to the 14 March opposition and the Hariri family, part of the anti-Syrian opposition.Blaming neighbourPresident Michel Suleiman and Prime Minister Mikati - who has faced calls for his resignation over the killing - greeted Mr Hassan’s coffin at an earlier ceremony at the headquarters of the Internal Security Forces (ISF).