Media playback is unsupported on your device Media caption Paul Wood, and cameraman Fred Scott, were smuggled into Homs

An Arab and Western-backed resolution condemning the violent crackdown in Syria has been vetoed at the UN Security Council by Russia and China.

They rejected the draft as "unbalanced" hours after activists accused troops of killing at least 55 people at Homs.

Western countries said the move would encourage Syria's government to continue its violent clampdown.

A BBC correspondent who entered Homs with rebels after the vote says gun and shell fire can be heard in the city.

'Craven tyrant'

The draft resolution, supported by all 13 other members of the Security Council, had adopted an Arab League call for a "Syrian-led political transition to a democratic, plural political system".

Russia said it singled out the government of President Bashar al-Assad, and did not contain measures against armed opposition groups.

At the scene As we came into the city this afternoon we heard a lot of heavy machine-gun fire and there were a lot of unexplained explosions. We had to come in using a very elaborate route, escorted by activists who were bringing medical supplies and fresh blood donated a few hours earlier in the villages around Homs. There is some dispute over the number of people killed here but they are still finding bodies and we expect more funerals on Sunday. What does seem to have happened is that the Free Syrian Army have been pushed out of the suburb of Khalidiya, which bore the brunt of what the activists say was a heavy attack by the government side. The rebel fighters are now squeezed into one very small part of Homs, from where I'm speaking, and which expects to be assaulted by Syrian government forces next. Read Paul's report from Homs

Proposed Russian amendments to the text were described as "unacceptable" by the US ambassador to the UN, Susan Rice.

Ms Rice condemned the vetoes as "shameful". It showed, she said, how Russia and China aimed to "sell out the Syrian people and shield a craven tyrant".

"Any further bloodshed that flows will be on their hands," Ms Rice added.

Britain's Foreign Secretary William Hague said the Russian and Chinese approach "lets the Syrian people down, and will only encourage President Assad's brutal regime to increase the killing".

French President Nicolas Sarkozy said his country would not give up seeking a solution. "The Syrian tragedy must stop," he said.

Mohammed Loulichki, Morocco's ambassador to the UN and the sole Arab member of the current council, voiced "great regret and disappointment" that Moscow and Beijing had struck it down.

But Russia's Ambassador, Vitaly Churkin, insisted the draft resolution had lacked balance.

"Some influential members of the international community unfortunately... have been undermining the opportunity for political settlement, calling for a regime change, pushing the oppositionists to power," he said.

Russian Foreign Minister Sergei Lavrov is due to have talks with Mr Assad in Damascus on Tuesday.

Beijing's ambassador to the UN, Li Baodong, said the resolution would have been counter-productive.

Media playback is unsupported on your device Media caption US Ambassador Susan Rice: "For months this council has been held hostage by a couple of members"

"China maintains that, under the current circumstances, to put undue emphasis on pressuring the Syrian government... or impose any solution will not help resolve the Syrian issue," he said.

Pro-Assad residents in the Syrian capital Damascus welcomed the Sino-Russian stance.

"I believe there are more important issues for the Security Council to take care of... such as the starvation in Somalia, and Gaza," one told BBC News.

"Isn't there anything else apart from us for the Security Council to deal with?"

Cut off

Early accounts of the casualties in Homs talked of as many as 200 deaths, but one of the main activist groups later revised its confirmed toll down to 55.

Fighting in Homs continued into the evening, the BBC's Paul Woods reports from a rooftop in a suburb of the city.

Our correspondent and his cameraman heard a lot of heavy machine-gun fire and unexplained explosions when they entered the city during the afternoon, travelling with activists who were carrying supplies of fresh blood to treat casualties.

The city appeared to have come under a "pretty relentless" bombardment on Friday, our correspondent adds, and parts of the city which oppose the regime have been cut off.

Ammar, a Homs resident, told the Associated Press news agency: "A few more nights like this one and Homs will be erased from the map."

Homs was one of the first cities to join anti-Assad protests, and became one of the focal points of dissent after government forces fired on crowds in April last year. Many army defectors have sought refuge in the city.

State media dismissed the Homs casualty reports as a "hysterical campaign of incitement" by armed gangs designed to influence the UN.

International media outlets are restricted in Syria, making it difficult to verify the claims of either side.

Tunisia moved to sever relations with the Assad government following the Homs violence

Activists have been attacking Syrian embassies around the world in response to the violence in Homs.

Syria has been gripped by nationwide protests against Mr Assad's government for almost a year, in a struggle that has claimed at least 5,400 lives, according to the UN.