|Activists released this picture of anti-government demonstrators marching in Idlib in northwest Syria on Friday [AFP]
Syrian security forces have clashed with protesters, killing at least 30 people as thousands have rallied across the country calling for President Bashar al-Assad to step down, activists say.
There were reports that the security forces opened fire on protesters at several of the demonstrations on Friday, and that there were also clashes between troops who have joined the protesters and those loyal to Assad.
Protests were reported in suburbs of Damascus, the capital, as well as in the southern province of Deraa, the northwestern province of Idlib, in Hama, Homs and several other cities.
An opposition activist, speaking to Al Jazeera on condition of anonymity, described the scene at one protest in Damascus: "The area where I stay now, a protest went around and it was soon attacked by security forces, and the attack included batons, hitting with batons, some gas bombs and later live ammunition that was shot all around.
"At least one person was injured. Later, after that, we could see a number of soldiers - we could see a clash between the soldiers and the security forces. And my friends confirmed that eight soldiers at least defected and shot back on the security forces."
'Defections' in al-Rastan
Many of the protesters were seen expressing solidarity with residents of the town of al-Rastan, just north of Homs, where fighting has been raging for three days between pro- and anti-government troops.
State media say seven government soldiers have been killed and 32 wounded in those clashes, and that the army had "inflicted big losses on the armed terrorist groups".
A military official told the state news agency SANA on Friday that the clashes were with "gunmen" rather than army soldiers who had broken ranks, and that they had been terrorising citizens, blocking roads and setting up barriers and explosives in the town.
The clashes in the town were making it difficult for aid to reach civilians in the town, activists said.
In-depth coverage of escalating violence across Syria
"People seriously wounded in Rastan were unable to receive medical care because of the continuing military operations," the Syrian Observatory for Human Rights, a London-based organisation, said.
Clashes were also reported in nearby Talbiseh on Friday.
Amateur videos posted online by activists showed thousands of people shouting in support of the army defectors in al-Rastan, which is home to 40,000 and located 180km north of Damascus.
"Rastan will overthrow the regime," read one banner waved by protesters in the Damascus neighbourhood of Qadam.
Many protesters covered their faces with scarves or masks to hide their identities, attempting to escape any possible backlash from security forces.
Army defectors 'a cover'
The Syrian government has banned most foreign journalists from entering the country and placed heavy restrictions on local media coverage, making it difficult to independently verify events on the ground.
The UN estimates that about 2,700 people have been killed in a violent government crackdown on pro-reform protests that began mid-March.
The government says that the movement against Assad does not have popular support and blames violence on "armed terrorist groups". It says that more than 700 soldiers and police have been killed in the uprising.
An army defector operating in the province of Idlib, northwest of al-Rastan, told the Reuters news agency that defectors were using guerrilla tactics against the heavily armed loyalist forces.
Activists say up to 1,000 army soldiers deserted to join the protesters in al-Rastan, but that figure is disputed.
"There are at least 100 army defectors in Rastan and 600 gunmen," one activist, speaking on condition of anonymity, told Reuters.
"The defectors are forming a cover for the gunmen so that everybody can say this is the army fighting among itself."
The Damascus-based activist who spoke to Al Jazeera claimed that there were as many as 10,000 members of what he called the "Free Syrian Army" across the country.
Elias Hanna, a retired Lebanese army general and security analyst, told Al Jazeera that it so far appears that the number of desertions is "not really causing a major crack within the Syrian army".