BEIRUT // A suicide bomber struck the National Security building in the Syrian capital today, killing the defence minister and President <a href="gopher://topicL3RoZW5hdGlvbmFsL1Blb3BsZS9MZWFkZXJzIGFuZCBwb2xpdGljaWFucy9CYXNoYXIgYWwgQXNzYWQ=" inlink="topic::L3RoZW5hdGlvbmFsL1Blb3BsZS9MZWFkZXJzIGFuZCBwb2xpdGljaWFucy9CYXNoYXIgYWwgQXNzYWQ=">Bashar Al Assad</a>'s brother-in-law in the harshest blow dealt to the Syrian regime since the uprising began. Syrian state-run TV said the blast came during a meeting of cabinet ministers and senior security officials in Damascus, where four straight days of clashes pitting government troops against rebel forces have sent tensions soaring. Defence minister Dawoud Rajha, 65, is the most senior government official to be killed in the Syrian civil war as rebels battle to oust Mr Assad. General Assef Shawkat, the deputy defence minister and one of the most feared figures in Mr Assad’s inner circle, was also killed. He was married to Mr Assad’s older sister, Bushra. Mohammed Shaar, the interior minister, was wounded and in stable condition, state TV said. Syria's rebel Free Syrian Army (FSA) claimed responsibility for the attack, but made no reference to how the officials were killed. Rajha, a former army general, was the most senior Christian government official in <a href="gopher://topicL3RoZW5hdGlvbmFsL0xvY2F0aW9uL01pZGRsZSBFYXN0L1N5cmlh" inlink="topic::L3RoZW5hdGlvbmFsL0xvY2F0aW9uL01pZGRsZSBFYXN0L1N5cmlh">Syria</a>. Assad appointed him to the post last year. His death will resonate with Syria’s minority Christian population, who make up about 10 per cent of Syria’s population and have generally stood by the regime. Damascus-based activist Omar Al Dimashki said Republican Guard troops surrounded the nearby Al Shami Hospital where some officials were taken for treatment. Facing increasingly chaotic violence, the UN Security Council was scheduled to vote later on Wednesday on a new resolution aimed at pressuring the Syrian regime to comply with a peace plan. But Russia remained at loggerheads with the US and its European allies over any mention of sanctions and Chapter 7 of the UN charter, which could eventually allow the use of force to end the conflict in Syria. Besides a government crackdown, rebel fighters are launching increasingly deadly attacks on regime targets, and several massive suicide attacks this year suggest Al Qaeda or other extremists are joining the fray. Activists say more than 17,000 people have been killed since the uprising began in March, 2011. The state-run news agency Sana reported that Wednesday’s blast was aimed at the National Security building, a headquarters for one of Syria’s intelligence branches and less than 500 metres from the US Embassy. Police had cordoned off the area, and journalists were banned from approaching the site. Earlier on Wednesday, Sana said soldiers were chasing rebels in the Midan neighborhood, causing “great losses among them”. The Britain-based Syrian Observatory for Human Rights said army helicopters attacked the neighborhoods of Qaboun and Barzeh. Diplomacy so far has failed to stop the bloodshed, and there appeared to be little hope that the UN’s most powerful body would unite behind a plan. The key stumbling block is the Western demand for a resolution threatening non-military sanctions and tied to Chapter 7 of the <a href="gopher://topicL3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvVW5pdGVkIE5hdGlvbnM=" inlink="topic::L3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvVW5pdGVkIE5hdGlvbnM=">United Nations</a> Charter, which could eventually allow the use of force to end the conflict in Syria. Russia is adamantly opposed to any mention of sanctions or Chapter 7. After Security Council consultations late Tuesday on a revised draft resolution pushed by Moscow, Russia’s deputy UN ambassador Alexander Pankin said these remain “red lines.” Russia has said it will veto any Chapter 7 resolution, but council diplomats said there is still a possibility of last-minute negotiations.