Syria crisis: Forces tighten grip on Baba Amr in Homs

Communication with the area has been largely cut off, and people are struggling to get in or out.

Syrian officials said their forces were "mopping up", but activists insisted the attack had been repelled.

Meanwhile, the new UN-Arab League envoy to Syria, Kofi Annan, called for unity behind a single mediation effort.

"If we are going to succeed it is extremely important that we all accept that there should be one process of mediation," he said.

"When you have more than one and people take their own initiatives the parties play with the mediators."

Russia and China have both vetoed UN resolutions on Syria and have also sent envoys to Damascus in recent weeks.

Mr Annan, who was installed by the UN and Arab League to try to broker a peace deal, said he was seeking talks with Syrian President Bashar al-Assad.

The BBC's Jim Muir says the Syrian opposition and its international allies have so far ruled out dialogue with the regime, so Mr Annan's more balanced approach may make it hard for Damascus to close its doors to him.

Separately, the UN's Human Rights Council is expected to pass a resolution later condemning the "brutal actions of the Syrian regime".

And the foreign ministers of the six Gulf Arab states say they will meet Russian Foreign Minister Sergei Lavrov next week to "express disappointment with the Russian stance", according to the AFP news agency.

The Gulf states have been vocal in their criticism of Syria's crackdown, while Moscow is seen as the regime's closest ally.

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