At least 100 people were killed in Syria on Tuesday during assaults on villages and a sustained bombardment on the city of Homs – according to activists.

As the crackdown on opposition protesters appears to intensify, including areas in the capital, Western and Arab pressure is mounting on President Bashar al Assad’s regime.

Washington, which is preparing for Friday’s inaugural meeting of a “Friends of Syria” contact group in Tunisia, has declined to rule out providing arms to rebels seeking to overthrow him.

“If we can’t get Assad to yield to the pressure that we are all bringing to bear we may have to consider additional measures,” said Victoria Nuland from the US State Department.

The International Red Cross is still waiting for a response from the Syrian government to its call for daily ceasefires to allow in urgently needed aid.

Russia is refusing to attend the Tunisia meeting as the Assad government will not be represented. Instead it is backing the president’s plans to hold a referendum on Sunday on a new constitution.