Syria conflict: Fresh offensive against rebels
Syrian troops have been mobilised in a drive to oust armed rebels from parts of Damascus, a day after a bomb attack that killed three top regime figures.
Tanks, artillery and helicopters have been deployed and clashes reported south-west and north-east of the city.
In a first public appearance since the bomb, President Assad was shown on TV swearing in the new defence minister.
Russia and China have vetoed a UN Security Council resolution calling for tougher sanctions on Syria.
Under the Western-backed plan, the Damascus government would have been threatened with non-military sanctions under Chapter 7 of the UN Charter if it failed to move troops and heavy weapons from populated areas.
It is the third time that Moscow and Beijing have vetoed sanctions against Syria.
With sporadic battles breaking out for control of Damascus, international envoy Kofi Annan has pushed the international community to take urgent and decisive action.
The Security Council must also decide whether to renew the mandate of a UN mission in Syria, due to end on Friday.
The bombing at Syria's national security headquarters claimed the lives of three high profile figures in President Assad's defence establishment
- Defence Minister and ex-chief of staff Gen Daoud Rajiha
- Deputy Defence Minister Assef Shawkat, married to Mr Assad's sister Bushra
- Assistant to the vice-president and head of crisis management office Gen Hassan Turkomani
- Two other senior officials - interior minister Mohammad Ibrahim al-Shaar and National Security Bureau chief Hisham Ikhtiar- were wounded
Rebel groups said the bomb had been planted the day before the meeting at national security headquarters where it was detonated. They predicted the government's imminent fall.
In contrast with earlier explosions in Damascus, there were no photos or video from the scene.
After the attack the government vowed to root out ruthlessly what it described as armed terrorists backed by outside powers.
Our correspondent says that video of one attack posted on the internet showed scenes of pandemonium after what activists said was a helicopter gunship attack on a funeral procession at Sitt Zeinab, south of the capital. They said at least 60 people were killed in this incident alone.
Activists also said there was fighting near the cabinet office on the western side of Damascus.
In the capital itself, state media said, security forces launched operations in many areas which have seen clashes in recent days, killing many "terrorists".
Activists reported more tanks moving towards the capital from the west.
But our correspondent says the rebels are on the offensive too, warning state TV and radio to evacuate staff before its headquarters comes under attack.
The London-based Syrian Observatory for Human Rights said on Thursday that more than 150 people had died across the country on Wednesday, in one of the worst days of a 16-month revolt.
The head of the UN monitoring mission, Gen Robert Mood, condemned the attack and said he had sent condolences to the victims' families.
"It pains me to say, but we are not on the track for peace in Syria and the escalation we have witnessed in Damascus over the past few days is a testimony to that," he said.
The US said the killings were a major blow to the regime.
"I think the incident today makes clear that Assad is losing control," White House spokesman Jay Carney told reporters. "All of our partners internationally need to come together to support a transition."
UK Prime Minister David Cameron said Mr Assad should step down and that it was "time for transition in the regime".
In Lebanon, Hezbollah leader Hassan Nasrallah condemned what he termed a targeted killing: "We are going to miss them and we offer our condolences to the Syrian leadership and the Syrian army."
Russia said some countries had incited the opposition rather than calming it down.