Rebels battle in heart of Damascus

Syrian rebels battled deep into the heart of Damascus today against government troops, who unleashed artillery and helicopter gunships on their own capital in retaliation for the assassination of Bashar al-Assad's closest security officials.

Diplomatic efforts that have long overtaken by events on the ground collapsed in disarray when Russia and China vetoed a UN Security Council resolution that would have imposed sanctions on Syrian authorities unless they stop using heavy weapons.

Washington said the council had "failed utterly".

The 16-month conflict - already in a climactic phase with rebels battling their way into the centre of the capital - has been completely transformed by a bomb that killed top members of Mr Assad's inner circle yesterday.

Mr Assad's powerful brother-in-law, his defence minister and a top general were killed, while the head of intelligence and the interior minister were wounded in the attack on a crisis meeting inside a security headquarters.

Mr Assad's own failure to appear in public in the next 24 hours - he was shown at last today in television pictures of the swearing in of a replacement for his slain defence minister - compounded the sense of his power eroding.

A woman who visited the neighbourhood of Tadamon, a scene of heavy fighting, said a police station was destroyed.

"I saw five charred bodies strewn across the street," she told Reuters by telephone. "Seven police cars were torched ... some mosques in Damascus are calling on loudspeakers which shelters are available for people who have fled."

Residents said a heavy onslaught of security force shelling and firing from helicopters went on through the night and continued today in Damascus.

Some reported explosions in the capital's troubled northeastern and southern districts.

A witness said rebels attacked the main police headquarters in Damascus.

"Gunfire has been intense for the past hour. It is now dying down but the streets around the police command remain empty," said a resident of Qanawat, an old central district where the Damascus Province police headquarters is located.

Other parts of the city were paralysed. Homes and shops were shuttered as Damascenes feared violence. Lebanese officials said refugees were pouring across the frontier. A security source said 20,000 Syrians had crossed.

International diplomacy has been ineffective throughout the crisis, with Western

countries condemning Mr Assad but lacking the stomach for the sort of robust intervention that saw Nato bombers help blast Libya's Muammar Gadafy from power last year.

Today's failed UN Security Council resolution, which would have extended a small, unarmed UN monitoring mission, was the third that has been vetoed by Russia and China.

The US ambassdor to the United Nations, Susan Rice, said the Security Council had "failed utterly", and Washington would look outside the body for ways "to bring pressure to bear on the Assad regime and to deliver assistance to those in need".

"The United States has not, and will not, pin its policy on an unarmed observer mission that is deployed in the midst of such widespread violence and that cannot count on even the most minimal support of this Security Council.

"Britain proposed a new four-paragraph resolution that would extend the mission for another 30 days, that could be voted on later today, diplomats said.