Protests accross Syria against President Bashar al-Assad continued after Friday prayers.
Syrian forces pounded the battered city of Homs with tank and mortar fire and troops pummelled several other rebel strongholds, leaving at least 24 dead, opposition activists have said.
With the bloodshed showing no signs of abating, the UN-Arab League peace envoy for Syria, Kofi Annan, flew to Moscow on Saturday, seeking Russian backing for his efforts to secure a ceasefire.
Activists reported heavy shelling on Homs' Khalidiyah neighbourhood and the city's old districts in an attempt by the government to regain control of opposition-stronghold pockets.
In al-Qusair town of Homs province, an activist network said the government's military campaign was continuing for a fourth day. The Syrian Revolution General Commission said the shelling had left several homes ablaze and thick smoke filled the sky.
Meanwhile, the UN-Arab League envoy to Syria, Kofi Annan, has arrived in Moscow.
Annan will try to persuade Russia to take a firmer stance against the Syrian government. Next week, he will travel to China which, like Russia, has generally supported Syria at the UN.