Syrian government forces "shell parts of Damascus" in wake of bomb attack GOVERNMENT forces in Syria are shelling a number of neighbourhoods in and around Damascus today, activists are reporting. Yesterday a bomb attack killed President Assad's brother-in-law and the defence minister David Cameron urges Syrian regime to go The renewed violence in the capital comes the day after three members of President Bashar Assad's inner circle were killed by a bomb The reports of shelling today come from the Britain-based Syrian Observatory for Human Rights. It says residents are fleeing parts of the Mezzeh neighbourhood after troops surrounded it and clashed with local rebels. This morning, Prime Minister David Cameron called on Assad to go. The whereabouts of Assad, his wife and three young children remain unknown after yesterday's bombing struck at the heart of his power. Speaking in Kabul, Mr Cameron said: "I have a very clear message for President Assad. It is time for him to go. It is time for transition in this regime. Clearly, Britain doesn't support violence on either side, but if there isn't transition it's quite clear there's going to be civil war. That is the clear fact, I think, that we can all see on the ground. The regime has done some truly dreadful things to its own people and I don't think any regime that carries out acts as they have against their own citizens - and continues to do so, by the way - should survive. I think that regime should go. "So the message to President Assad is "It is time for transition, it is time for you to go." "The message to President Putin, who I discussed this with at the G20 in Mexico - and the message to all those on the UN Security Council - is "It's time for the UN Security Council to pass clear and tough messages about sanctions, I believe under Chapter 7 of the UN, and to be unambiguous about this." Obviously, we are a UN Security Council with permanent members, and permanent members that have vetoes. We can't pass these things without everybody stepping up to the plate and taking the right action. But I would appeal to those who in the past have held against tough action against Syria - what more evidence do we need about a regime that has brutalised its own people? The alternative to political transition at the top of Syria is revolution from the bottom in Syria. Rebels claimed responsibility for yesterday's attack, saying they had been planning it for two months and finally decided to plant the bomb in the room where the senior government security officials in charge of crushing the revolt were holding the meeting. Syrian TV yesterday confirmed the deaths of defence minister Dawoud Rajha, 65, a former army general and the most senior government official to be killed in the rebels" battle to oust Assad; General Assef Shawkat, 62, the deputy defence minister who is married to Assad's elder sister, Bushra, and is one of the most feared figures in the inner circle; and Hassan Turkmani, 77, a former defence minister who died of his wounds in hospital. Also wounded were interior minister Mohammed Shaar and Major General Hisham Ikhtiar, who heads the National Security Department.