In the north-western city of Idlib near the Turkish border, seven members of the security forces, five army rebels and three civilians were killed, the Syrian Observatory for Human Rights (SOHR) said.
Five civilians were shot dead by security forces in central Homs province, and a man’s body, who was picked up by security forces some five days back, was returned to his family.
The United Nations’ top human rights forum has condemned Syria for “gross and systematic” violations by its forces, including executions and the imprisonment of some 14,000 people.
Syrian authorities say they are fighting foreign-backed “terrorist groups” trying to spark civil war who have killed some 1,100 soldiers and police since March.
The Arab League, which has deepened Assad’s isolation by announcing economic sanctions against Damascus, gave Syria until Sunday to sign an initiative to end the crackdown, Qatar’s foreign minister said.
He did not explicitly say when the sanctions would come into force, but said they would be imposed soon if Syria does not sign the deal, which includes Arab monitors to ensure that Damascus abides by a promise to end violence.