Further north in Hama, four civilians were shot, while seven people were killed in the town of Kanaker, outside the capital, and a protester was shot dead by security forces in Damascus.
Two more people were killed, one of them an army deserter, when troops opened fire on a group of people trying to slip across the border into Jordan, the Britain-based Observatory said.
Four policemen were also wounded, two critically, in clashes with an "armed terrorist group" in Kanaker, the state-run SANA news agency reported, adding that one of the gunmen was killed in the fighting.
The agency also denied reports that dozens of people were arrested in Banias, quoting the governor of Tartus where the Mediterranean coastal city is located.
Earlier the Observatory said that "four children closely related to Observatory director Rami Abdel Rahman" were among those seized in Banias.
Video footage posted on YouTube showed dozens of demonstrators, some masked, marching through the historic Midan neighbourhood of Damascus, chanting anti-Assad slogans.
Protesters in Harasta just outside Damascus, described Assad as a "liar" who has no intention of implementing the Arab roadmap.
Demonstrators also chanted: "Allah will overcome tyrants and despots" -- echoing the slogan of Friday's protests which activists called to "validate" whether the government was implementing terms of the Arab peace deal.
The United States and France slammed Syria for pressing on with its crackdown on dissent and failing to heed to the hard-won agreement that calls for tanks to be withdrawn from protest hubs in a bid to end nearly eight months of bloodshed.
Members of the UN Human Rights Council meanwhile said they seek to "shine a spotlight" on violations in Syria as a UN commission of inquiry prepared to file later this month a report on the violence-wracked country.
France said Syria was breaking its commitments to the Arab deal by continuing a deadly crackdown on protesters, and cast doubt on President Bashar al-Assad's dedication to the deal.
There has been enormous scepticism inside and outside Syria about the regime's readiness to call off its troops and enter meaningful negotiations with the opposition as it promised under the deal unveiled on Wednesday.
"The continuing repression can only strengthen the international community's doubts about the Syrian regime's sincerity to implement the Arab League peace plan," French foreign ministry deputy spokesman Romain Nadal said in Paris.
In Washington US State Department spokeswoman Victoria Nuland on Thursday said: "We have not seen any evidence that the Assad regime intends to live up to the commitments that it's made."
On Friday she also expressed scepticism of an amnesty announced by the interior ministry to mark the end of the annual Muslim hajj, or pilgrimage, and the start Sunday of Eid al-Adha feast.
"I wouldn't advise anybody to turn themselves in to regime authorities at the moment," said Nuland amid apparent concerns for the welfare of those who might do so.
State media reported that anyone heeding the ministry's call to surrender weapons at the nearest police station "will walk free.. and receive an amnesty."
The interior ministry established a deadline from Saturday to November 12 but warned the offer was not valid for anyone having committed "murder."
Syrian authorities have used force to crush almost daily anti-regime protests since mid-March, and more than 3,000 people have been killed according to UN estimates.
Pro-democracy protesters insist their campaign is peaceful while the government says it has been battling "armed terrorist groups."
The Arab League meanwhile took Syria to task and said foreign correspondents should apply to Syrian authorities to enter the country, since unfettered media access was part of the deal Damascus approved.
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