Syrian forces renewed their assault on the rebel city of Homs as Russia's foreign minister talked of the need for reform with President Bashar Assad over the country's escalating violence.

Sergey Lavrov's visit came days after Syrian allies Russia and China vetoed a resolution at the United Nations that would have condemned the Assad regime's crackdown on dissent and called on him to transfer some of his powers to his deputy.

"Necessary reforms must be implemented in order to address legitimate demands of the people striving for a better life," Mr Lavrov told Assad.

He also said Assad was ready for talks with the opposition.

"It's clear that efforts to stop the violence should be accompanied by the beginning of dialogue among the political forces," he said. "Today we received confirmation of the readiness of the president of Syria for this work."

Repeated efforts by the Arab League and Russia to broker talks have been rejected by the Syrian opposition, which refuses to hold talks amid the crackdown and says it will accept nothing less than the regime's downfall.

The violence, meanwhile, continued with regime forces keeping up an assault on Homs, Syria's third largest city. Activists reported that at least 15 people, including a 15-year-old boy, were killed in violence across the country.

More than 5,400 people have been killed in Syria since the uprising began in March, the UN said early last month. Hundreds more are believed to have been killed since then, but the UN says the chaos in the country has made it impossible to cross-check the figures.

Meanwhile The six-nation Gulf Co-operation Council said that it was pulling its ambassadors from Syria because of Assad's refusal to accept Arab attempts to end the bloodshed. The GCC, which includes Sunni powerhouse Saudi Arabia, as well as Bahrain, Kuwait Qatar, Oman and the United Arab Emirates, also said it was asking Syria to recall its ambassadors.

Also, France, Italy and Spain announced they were recalling their ambassadors to Syria for consultations - in what appeared to be coordinated European diplomatic pressure to isolate Assad as the Russian foreign minister arrived. The US closed its Damascus embassy on Monday, while Britain recalled its ambassador.