Heavy clashes and air strikes shook Syria's rebel enclave of Eastern Ghouta on Sunday despite a UN call for a ceasefire to end one of the most ferocious assaults of Syria's civil war. After days of diplomatic wrangling, the Security Council on Saturday adopted a resolution calling for a 30-day ceasefire in Syria without delay, to allow for aid deliveries and medical evacuations. President Bashar al-Assad's forces launched a major bombing campaign against the enclave on the edge of Damascus a week ago, with over 500 people killed so far. However, the UN resolution remains unclear as to when and how broadly the ceasefire could be implemented. Russia is a key ally of Assad's regime and in a phone call on Sunday German Chancellor Angela Merkel and French President Emmanuel Macron urged President Vladimir Putin to use his influence. They called on Russia to exercise maximum pressure on the Syrian regime to achieve an immediate suspension of air raids and fighting, Merkel's office said in a statement. Reportedly, seven civilians were killed in strikes on Sunday, bringing the total number of dead in the week to 527, including 129 children. Although there appeared to be fewer air strikes, Observatory chief Rami Abdel Rahman said, fighting had intensified on the ground. Heavy clashes erupted in southern areas of Eastern Ghouta, he said, with at least 13 members of pro-regime forces and six fighters from the Jaish al-Islam rebel group killed.