BEIRUT: A suicide bombing in Damascus claimed the lives of President Bashar Assad’s brother-in-law, his defense minister and a former defense minister and wounded a number of other security officials Wednesday, in the boldest attack in the 16-month revolt against Assad’s regime.

Syrian official media reported Gen. Dawoud Rajha, the country's defense minister, and Gen. Assef Shawkat, army deputy chief-of-staff, were killed as a result of the suicide blast that targeted a security meeting at the National Security headquarters in the capital.

Syrian Vice-Presidential aide and former Defense Minister Hasan Turkmani also died of wounds sustained in the attack, Syria’s state news agency said.

The attack was claimed by both the Free Syrian Army and an Islamist group.

Rajha is the highest profile pro-Assad figure to be killed during the 16-month unrest in the country.

The 64-year-old was the army’s chief of staff before assuming the post of defense minister in August 2011.

U.N.-Arab League envoy Kofi Annan – who has tried to resurrect his peace bid to end the conflict in Syria – asked the U.N. Security Council to delay a vote scheduled for Wednesday on a Western-drafted resolution calling for sanctions against Syria, British diplomats said.

“Joint Special Envoy Annan has asked to delay today’s draft Syria resolution vote. With fellow co-sponsors we're considering that request,” a U.K. spokesman said in a statement posted on micro-blogging site Twitter.

The Syrian regime said it would punish those behind the bomb attack, which also wounded the country’s interior minister, Mohammad Shaar.

"The armed forces are determined to terminate the killing gangs and criminals and pursue them wherever they go," said the military, in a statement read out on state television, vowing it would "chop any hand that harms national security."

"Whoever thinks that by targeting some commanders they can twist Syria's arm, is delusional,” the statement added.

The suicide bomber was a bodyguard for Assad’s inner circle, Reuters, quoting a Syrian security source, reported.

Other senior security officials were wounded, some critically, in the blast at the meeting, according to Syrian media.

Hezbollah’s Al-Manar television, quoting Syrian sources, reported that National Security chief Hisham Bakhtiar and Mohammad Said Bakhtian, the national secretary of the Baath Party, were also wounded in the attack.

The bombing comes as Syrian rebels launched earlier this week what they described as their push to “liberate” the Syrian capital.

A Syrian rebel Islamist group called Liwa Al-Islam claimed responsibility for the Damascus explosion, in a Facebook statement.

The main rebel group, the Free Syrian Army, later claimed responsibility for the deadly attack.

Assad, who in June said his country was in a state of war, appointed Gen. Fahed Jassem al-Freij as the new defense minister.

In a video posted online in May, the “Special Operations Company of the Al-Sahabah Battalions” – a group linked to the FSA - said it had carried out a covert military operation against Rajha, Shawkat, Shaar, Turkmani, Bakhtiar and Bakhtian, who it said were part of a so-called “crisis cell.”

A spokeswoman for the Revolutionary Council for Damascus told a British newspaper that the method of attack was poisoning and that it was unclear how many of the men were injured or dead.