Syrian president Bashar Assad has defended his government’s crackdown on opponents, saying a doctor performing emergency surgery does not have blood on his hands if he is trying to save a patient.

Syrian president Bashar al-Assad yesterday defended his government’s crackdown on opponents, saying a doctor performing messy emergency surgery does not have blood on his hands if he is trying to save a patient.

Syrian president Bashar Assad has denied his government had anything to do with last week's Houla massacre, saying not even "monsters" would carry out such an ugly crime.

At least seven people were killed and 22 others injured in gun battles between pro- and anti-Syrian groups in northern Lebanon today, security officials said, as activists reported fresh shelling in a region in central Syria where a massacre last week left more than 100 people dead.

The UN's top human rights body has voted overwhelmingly to condemn Syria over the slaughter of more than 100 civilians last week.

Gunmen have killed 11 workers at a state factory in central Syria, activists say, the second execution-style shooting reported in the country in less than a week.

The US is heaping new pressure on Russia to change course and support international action in Syria, warning that intransigence by Moscow may lead to open civil war that could spill across the Middle East with devastating consequences.

Syrian troops today shelled the central region of Houla where more than 100 people were massacred last week, activists said.

UN observers have found another 13 bound corpses in eastern Syria, many of them seemingly shot execution- style, said the monitoring mission.

The UN peacekeeping chief said today there are strong suspicions that pro-regime fighters were responsible for some of the 108 victims of a massacre in Syria, along with heavy weapons illegally fired by government forces.

The weekend massacre of more than 100 people became a potential turning point in the Syrian crisis yesterday as even staunch ally Russia took an unusually hard line against President Bashar Assad’s government.