Syrian security forces shot dead at least six people on Friday as they opened fire to disperse protesters urging countries to expel Syria's ambassadors, activists said.
Meanwhile SANA, the state news agency, quoted an official source as saying two members of the security forces were killed and an officer was critically wounded in a bomb blast in the restive central city of Hama.
The latest bloodletting comes on the eve of a deadline by the Arab League for Syria to stop the lethal crackdown on protesters seeking the ouster of President Bashar al-Assad's regime, or face new sanctions.
Three people were killed in the Damascus countryside, while one was shot in the central protest city of Homs and another in the restive city of Hama, also in the centre of the protest-wracked country, the Syrian Observatory for Human Rights reported.
A 14-year-old boy was shot dead in the southern town of Daraa, cradle of the uprising against Assad's autocratic regime, said the Britain-based Observatory.
More than 20 people were shot and wounded in Homs, in the Damascus suburb of Harasta and in Maaret Numan in the northwestern province of Idlib, the Observatory and the opposition Local Coordination Committees (LCC) reported.
Activists reported massive deployments of security forces in several parts of the country and said they had surrounded mosques to prevent worshippers from spilling onto the streets after the weekly Muslim prayers to join protests.
They opened fire as several rallies got under way in defiance of the authorities, in Homs, Daraa and in several areas of the eastern province of Deir Ezzor, they said.
In the Idlib town of Al-Tah, protesters flooded the streets calling for the fall of the regime and chanting: "Freedom forever, like it or not Assad."
The Observatory also reported that 16 people were arrested in raids by security forces in Maaret Numan.
Activists had called for massive protests on Friday to press countries to expel Syrian ambassadors, to further isolate Damascus which is faced with Western and Arab sanctions.
"They are the ambassadors of crime. Expel them, oh free ones," the Syrian Revolution 2011, one of the main groups behind the protests, said on its Facebook page.
Another umbrella group of activists, the Syrian Revolution General Commission, also called for nationwide protests "until the regime falls."
Meanwhile the LCC reported that the SANA director in Deir Ezzor, Alaa al-Khodr, "resigned in protest over the regime's actions towards civilians."
"Khodr taped his mouth shut and wore a sign that said: 'I am a Syrian journalist'," the LCC said in a statement received in Nicosia.