Syrian opposition activists have appealed to the international community to increase pressure on the regime of President Bashar al-Assad as condemnation mounts over escalating bloodshed.

Omar Habal from the central city of Hama, where four more people were reportedly killed by shellfire on Monday, said protestors wanted foreign governments to withdraw their ambassadors from Damascus and expel Syrian diplomats from their capitals in response to a brutal crackdown in which more than 100 people were killed across Syria on Sunday.

"We want action but not military intervention, we don't need that," Habal told the Guardian by telephone. "We need pressure, strong political pressure."

The appeal came as the UN security council was preparing to meet in New York to discuss the crisis after rare condemnation of the violence by Russia, a long-time ally of Syria, as well as unusually harsh words from the leaders of its neighbour Turkey.

The US, Britain and France have all used strong language to condemn events on Sunday, the eve of Ramadan and the bloodiest day of the uprising so far.

Syria's opposition is divided, with some groups calling for the overthrow of the Assad regime while others still hope the president will launch genuine reforms.

Foreign governments say that Assad has lost legitimacy but have not explicitly and directly called for his overthrow.

"The international community needs to act quickly to prevent further atrocities in Syria," said Ausama Monajed, a leading exiled dissident. "What are they waiting for? A million Syrians to be killed? It is shameful by any standard to see human beings being shot and killed and not a single condemnation from the UN Security Council. What message does that send to brutal dictators?"

The EU announced on Monday that it had imposed travel bans and assets freezes on five unnamed Syrian officials, but measures imposed on 30 other senior figures have been shrugged off in Damascus.

Russia said it was "seriously concerned" about the level of casualties but implied government and opposition were equally at fault. "The use of force against civilians and representatives of state structures is unacceptable and must cease," the foreign ministry statement said. Western diplomats said it was unclear whether this meant Moscow was dropping its objections condemning Syria.

China has also been reluctant to back the US, Britain and France in demanding punitive gestures, let alone action. Moscow and Beijing are unhappy at the way their support for the UN at the start of the Libya crisis was turned into a mandate for a Nato bombing campaign they now see as pursuing regime change.

India, South Africa and Brazil have also opposed a resolution.

William Hague, Britain's foreign secretary, said he wanted a resolution to condemn the Syrian violence and admitted there was no possibility of military action of the type seen in Libya. "There is no prospect of a legal, morally sanctioned military intervention," he told the BBC.