Syrian security forces have opened fire on protesters, killing at least six people, as thousands rallied across the country to call for the downfall of President Bashar Assad's regime.
Troops also clashed with armed anti-regime forces in central regions for a third straight day.
The London-based Syrian Observatory for Human Rights said six people were killed in the central cities of Hama and Homs as well as the central town of Rastan, where the clashes between troops and army defectors have been raging for days. Syria-based rights activist Mustafa Osso put the death toll at 11.
The protests spread from the capital, Damascus, and its suburbs to the southern province of Daraa, the north-western province of Idlib as well as Hama and Homs.
Many of the protesters expressed solidarity with residents of the rebellious town of Rastan just north of Homs.
Amateur videos posted online by activists showed thousands of people shouting in support of the rebellion in Rastan.
"Rastan will overthrow the regime," read one banner waved by protesters in the Damascus neighbourhood of Qadam. Many of the protesters there covered their faces with scarves or masks to hide their identities.
The Syrian government has banned foreign journalists and placed heavy restrictions on local media coverage, making it difficult to independently verify events on the ground.
The UN says some 2,700 people have already died in the government crackdown against the uprising that began in mid-March.
The protests today followed the week's main Muslim prayer services and were similar to demonstrations held across Syria every Friday for the past six months since the uprising against Assad erupted in the country's south.
A military official said that two days of clashes between Syrian troops and anti-Assad forces in Rastan killed seven soldiers and policemen.
The official said 32 Syrian troops were also wounded in the fighting as government forces conducted a "qualitative" operation in an effort to crush "gunmen" holed up inside the town.
The government describes its armed opponents there as "terrorist armed groups," not army defectors.
The official said the gunmen had terrorised citizens, blocked roads and set up barriers and explosives, and were responsible for the deaths of the seven troops.
Rastan has witnessed some of the fiercest fighting in the six-month uprising against Assad, pitting the military against hundreds of army defectors, according to activists.
The town, from which the Syrian army draws many of its Sunni Muslim recruits, has seen some of the largest numbers of defections to date. A prominent human rights activist estimated there were around 2,000 defectors fighting in Rastan and nearby Talbiseh as well as in the Jabal al-Zawiyah region in the northern Idlib province.