Activists and residents say Syrian security forces have raided towns and villages in central Syria and near the Turkish border.
Several people were reported killed, but with foreign media banned from country it is impossible to verify figures.
Residents and local activists said the September 5 raids near Turkey were aimed to prevent people from fleeing across the border.
One person was reported killed by army snipers just after he had crossed into Turkey from a village on the Syrian side of the border.
Meanwhile, activists said troops backed by tanks raided the central towns of Homs and Hama.
Amid the latest violence, the head of the International Committee of the Red Cross (ICRC) sought to pressure the government to ensure medical access to those injured and jailed during the government's crackdown on a five-month-old uprising.
ICRC President Jakob Kellenberger met in Damascus with Syrian officials to discuss medical access to the injured, as well as ICRC access to detainees in Syrian prisons.
Activists said at least 12 people were killed by security forces on September 4 in northwestern and central Syria.
The state-run SANA news agency said at least nine people, including six soldiers, were killed when an "armed terrorist group" ambushed a bus in central Syria.
More than 2,200 people have been killed in Syria since almost daily protests began in March, according to United Nations' estimates, while human rights groups say more than 10,000 are behind bars.
compiled from agency reports