Syrian tanks mounted with machine-guns have reportedly opened fire on protesters one day after Damascus agreed to an Arab League plan calling on the government to pull the military out of cities.
Witnesses said a district in Homs, a city at the heart of the seven-month-old uprising, came under heavy fire.
Thousands have died since the uprising began as the government cracked down on protesters.
The report of today's violence came from Rami Abdul-Rahman, head of the British-based Syrian Observatory for Human Rights.