Syria rallies in support of army defectors
Syrians have held nationwide rallies in support of the Free Syrian Army, a group of army defectors seeking to topple President Bashar al-Assad.
Thousands of people reportedly took to the streets in the cities of Aleppo, Deir al-Zour, Homs, Hama, Idlib and many suburbs of the capital Damascus.
One activist group said 12 civilians were killed, three of them children.
Later, troops backed by tanks stormed the mountain town of Zabadani, near the border with Lebanon, witnesses said.
Kamal al-Labwani, a senior opposition figure from Zabadani who fled to Jordan two weeks ago, said communications had been cut, but that he had managed to speak to several people in the town.
"Tanks are bombarding the town and have entered the outskirts, but they are being met with resistance," he told the Reuters news agency. "The Free Syrian Army has strong presence in the area."
The Local Co-ordination Committees, an activist group that organises and documents protests, said the nearby town of Madaya was also being shelled, and that several people had been injured.
Children were earlier photographed at an anti-Assad rally in Zabadani.
Earlier, the UK-based Syrian Observatory for Human Rights said security forces had killed one protester in the central city of Hama, and another in the town of Ariha in the north-western province of Idlib, where more than 20,000 people showed their support of the Free Syrian Army.
The group also said about 15,000 people had gathered in the Damascus suburb of Douma, and that there had been violence in the southern province of Deraa and the eastern region of Deir al-Zour.
Explosions and heavy gunfire were also reported in the city of Homs.
The Local Co-ordination Committees said a total of 12 civilians had been killed nationwide on Friday, including five in Homs, and two each in Aleppo and the Damascus suburb of al-Dumair.
The LCC also said two foreign journalists and a translator had been arrested in Damascus, but gave no further details. The government has restricted access by most foreign media.
Opposition activists called for demonstrations in support of the Free Syrian Army a day after it agreed to co-ordinate its operations more closely with the main opposition coalition, the Syrian National Council.
An SNC statement issued on Thursday after its chairman, Burhan Ghalioun, met FSA leader Col Riyad al-Asaad said a liaison office would be set up to "maintain direct communications around the clock".
The groups also agreed to devise a plan which would include "the reorganisation of FSA units and brigades, and the creation of a format to accommodate within FSA ranks additional officers and soldiers, especially senior military officials, who side with the revolution", the SNC added.
The SNC initially opposed the use of force in the uprising against President Bashar al-Assad, while the FSA operated independently.
It is impossible to verify how many army defectors have joined the FSA, but Col Asaad has put the figure at 20,000.
The group has said it is behind attacks on Syrian security forces, and the authorities have acknowledged mounting losses.
The most senior military commander to have changed sides said desertions were wearing down the army, but that it could take the FSA more than a year to topple the president.
"If we get 25,000 to 30,000 deserters mounting guerrilla warfare in small groups of six or seven it is enough to exhaust the army in a year to a year-and-a-half," Gen Mustafa Ahmed al-Sheikh told Reuters news agency on Thursday.
The government says 2,000 security personnel have died combating "armed gangs and terrorists". The UN says more than 5,000 people have been killed by Syrian security forces since the uprising began in March.
Meanwhile, Syrian border guards have turned back several hundred activists who wanted to bring in humanitarian aid from Turkey. The guards said they did not have the right permits to enter the country.
The activists, who called themselves the "Freedom Convoy to Syria", said they would stage a sit-in protest close to the border.
A court in Paris has also opened an investigation into the death of a French television journalist in Homs on Wednesday.
The Paris prosecutor has asked for an autopsy on Gilles Jacquier, whose body has been brought back to France.
He was killed when a government-escorted convoy of journalists came under attack from rocket-propelled grenades.
Mr Jacquier's employer has said there are "troubling" details about the circumstances of his death.
"For instance.... why did the military suddenly disappear when the first shots were fired?" asked Thierry Thullier, the head of news at France Televisions.
Also on Friday, a Russian ship detained this week by Cypriot authorities because it was transporting "dangerous cargo" - thought to be ammunition - reportedly docked at the Syrian port of Tartous.
The vessel was allowed to leave Cyprus on Wednesday after giving written assurances that its destination would not be Syria.