BEIRUT — Fierce clashes broke out in Damascus, Syria, between rebel forces and the Syrian military Wednesday after a relative lull in fighting that lasted several weeks.Rebel fighters attacked forces loyal to President Bashar ¬al-Assad in Abaseen Square in central Damascus as well as in several neighborhoods surrounding the capital, according to opposition activists.But the official Syrian Arab News Agency issued a denial, saying reports of fighting in Damascus were "categorically baseless” and "desperate attempts intended to lift the morale of the terrorists.”Also Wednesday, two suicide car bombs struck offices of Syrian military intelligence and the Interior Ministry’s intelligence arm, the General Security Directorate, in the central city of Palmyra, killing at least 12 people and injuring more than 20, according to the Britain-based Syrian Observatory for Human Rights, a watchdog group that monitors the violence in the country.State media confirmed the attacks but said the car bombs targeted a residential area in the city. A video posted online shows a black plume of smoke over what appears to be a residential district shortly after one of the explosions.The stepped-up violence Wednesday came two days after Mouaz al-Khatib, head of the Syrian Opposition Coalition, called again on the Assad government to begin negotiating to end the civil war. Many prominent opposition activists have rejected any talks with the government before Assad steps down.