Syria's defence minister General Daoud Rajha
Rebels claimed a bomb attack which struck at the heart of Syria's senior command, killing at least three of President Bashar al-Assad's top brass and warned of more carnage to come, reports AFP.
The explosion, blamed on a bodyguard attending a meeting of security chiefs at their Damascus headquarters, prompted the White House to say Assad was "losing control" of Syria.
The attack, the first to target Assad's inner core since a 16-month uprising erupted, came ahead of a showdown between the West and Russia and China over a draft UN resolution calling for sanctions, which was pushed back till Thursday.
UN chief Ban Ki-moon urged the divided Security Council to "shoulder its responsibility and take collective and effective action" over the conflict, which activists say has killed more than 17,000 people since March last year.
Wednesday's bombing killed Defence Minister General Daoud Rajha, Assad's brother-in-law Assef Shawkat and General Hassan Turkmani, head of the regime's crisis cell on the uprising, state media said.
Among those wounded were Interior Minister Mohammed al-Shaar and General Hisham Ikhtiyar, head of National Security.
Conflicting accounts have emerged of who carried out the attack and how.
It was claimed by the rebel Free Syrian Army as its fighters battled Assad loyalists across Damascus for a fourth straight day, although another group, the Brigade of Islam, also said it was responsible.
The FSA command "announces the good news of the outstanding operation this morning that targeted the National Security headquarters and the killing" of the officials "responsible for barbaric massacres," it said.
The rebels said the attack, part of Operation Damascus Volcano launched on Monday, "is the first in a series... aimed at bringing down Assad and the pillars and symbols of the regime, whether civilian or military."
State media initially said it was a "suicide bombing" before apparently retracting and calling it a "terrorist attack."
A Syrian security official told AFP the bombing was carried out by a bodyguard of one of the ministers or security chiefs at the meeting. The attacker had been wearing an explosives belt.
Another official said the blast was caused by a briefcase packed with explosives that a bodyguard left in the meeting room and detonated from afar via remote control.
The FSA said in a YouTube video that six people died including Interior Minister Shaar, General Hisham al-Bikhtyar, head of the national security branch, and Mohammed Saeed al-Khitan, identified as "deputy local trustee."