RAGE: Syrian and Jordanian Islamist supporters shout anti-Syrian President Bashar al-Assad slogans during a protest in Amman yesterday. Picture: REUTERS

A SUICIDE bomb attack which killed several powerful members of Syrian President Bashar al-Assad's military establishment, including his defence minister, increased the urgency for tougher United Nations (UN) action, world leaders warned yesterday, as Russia said that a "decisive battle" was under way.

Mr al-Assad's brother-in-law, Assef Shawkat, and Defence Minister Dawoud Rajha, were killed in the blast with the vice-president's military adviser, Hassan Turkmani. Other officials including the interior minister were hurt, state television said. Maj-Gen Shawkat served as deputy defence minister and deputy chief-of-staff for security, and was part of Mr al-Assad's inner circle. Al Arabiya television said Mr al-Assad's cousin Hafez Makhlouf also died.

They are the most senior officials to be killed since the uprising started in March 2011, evidence of the growing threat to the al-Assad family's four-decade hold on power.

The UN and activists say about 17000 people have been killed in fighting in the capital.

But, with four straight days of fighting - some within sight of the presidential palace yesterday - Moscow said proposed UN sanctions or military action would worsen the violence. "A decisive battle is under way in Syria," Foreign Minister Sergei Lavrov said. "It is a dead-end policy to support the opposition. Al-Assad will not go on his own and our western partners don't know what to do about that."

US Defence Secretary Leon Panetta called for Mr al-Assad to step down, saying: "The violence there has only gotten worse and the loss of life has only increased, which tells us that this is a situation that's rapidly spinning out of control," he said.

The international community needed to "bring maximum pressure on (Mr al-Assad) to do what's right, to step down and allow for that peaceful transition," he said. Mr Panetta's comments to a Pentagon news conference followed closed-door talks with his UK counterpart, Philip Hammond.

Speaking alongside Mr Panetta, Mr Hammond said the situation in Syria was "becoming more and more unpredictable".

The rebel groups are mostly led by Sunni Muslims, who form the majority of Syria's population. Mr al-Assad and many of his top officials come from the Alawite minority, affiliated to Shiite Islam, with allies that include Iran.

"The death of Shawkat brings the violence very close to the regime," said Nadim Shehadi, associate fellow at the Royal Institute of International Affairs in London, adding: "He's one of the pillars."

Hours after the blast, Mr al-Assad appointed Jassem al-Fraij as defence minister, state reports said. Mr al-Fraij vowed to "cut the hand" of anyone who wanted to harm the nation. The military said "those who think they can bend Syria's arm by killing several leaders are delusional".

Rebel fighters, mostly armed with light weapons, have been pushing into the capital in the past few days to battle government forces armed with tanks, artillery and attack helicopters. Earlier yesterday, artillery shells slammed into areas of Damascus as security forces tried to dislodge the fighters.

UK Foreign Secretary William Hague yesterday condemned the attack, saying it "confirms the urgent need for a Chapter 7 resolution of the UN Security Council on Syria".

Along with the US, France and Germany, the UK tabled a UN Security Council resolution that would extend a UN observer mission in Syria for 45 days and place joint special envoy Kofi Annan's peace plan under Chapter 7 of the UN Charter. Chapter 7 allows the 15-member council to authorise actions from sanctions to military action.

US officials have said they are talking about sanctions.

"The situation in Syria is clearly deteriorating. All the members of the UN Security Council have a responsibility to put their weight behind the enforcement of Mr Annan's plan to end the violence," Mr Hague said.

German Chancellor Angela Merkel said the bombing "shows us that it is high time to ratify the next UN resolution", and French Foreign Minister Laurent Fabius said "this degree of violence . means that it is necessary and urgent to find a political transition that allows the Syrian people to have a government that expresses its aspirations".

Gala Riani, a Middle East analyst at Control Risks consultancy, said the suicide bombing was "in some ways the most successful direct attack on the regime we've had so far".

"I think the next few days are going to be crucial in signalling where the conflict goes from here," said Ms Riani.

Bloomberg, Reuters