Syrian forces killed at least seven people when they opened fire to disperse protests against President Bashar Assad after Friday prayers in Damascus and Homs, activists said.
Rami Abdel-Rahman, head of the British-based Syrian Observatory for Human Rights, said three people were killed in the Damascus suburb of Douma and four in Bab Sbaa, a district in the central city of Homs where Syrian troops fought army deserters and gunmen last week.
Activists said protesters also came under fire in the tribal region of Deir al-Zor on the border with Iraq and in the city of Hama.
Video footage showed protesters holding banners urging the international community to protect civilians.
Some chanted "Syria, Assad is a germ here" and "We do not love you (Assad), leave you and your party."
An activist told Al Jazeera television channel that Syrian protesters had burned the flags of Russia and China for blocking a European-drafted UN Security Council resolution urging Syria to end its six-month crackdown on protesters.
Russian President Dmitry Medvedev said on Friday the Syrian leadership should leave power if it is unable to implement promised reforms, the state-run RIA news agency reported.
"We are using our channels and are actively working with the Syrian leadership, we are demanding that the Syrian leadership implement the necessary reforms," Medvedev said.
"If the Syrian leadership is incapable of conducting such reforms, it will have to go, but this decision should be taken not in NATO or certain European countries, it should be taken by the Syrian people and the Syrian leadership."
While Assad has sent troops and tanks to crush protests, he has also promised reforms. He has ended a state of emergency and given citizenship to tens of thousands of Syrian Kurds. He has also promised a parliamentary election in February.
Many of Assad's opponents say his reform promises are hollow and that his government has forfeited all legitimacy after killing at least 2,900 civilians, by a UN count.
Want to enjoy 'Zen' reading - with no ads and just the article? Subscribe todaySubscribe now