Two protesters were shot dead on Friday as live fire was used to disperse hundreds of protesters in the Qatana suburb east of the capital Damascus, the Syrian Observatory for Human Rights said.
Also on Friday, Syrian forces fired at protesters calling for the "overthrow of the regime" in an eastern city, residents said, and world leaders voiced outrage at President Bashar Assad's bloody crackdown on popular unrest.
Leaders at a Group of Eight meeting in France said they were "appalled" at the killing of peaceful protesters - rights groups estimate at least 1,000 deaths over 10 weeks - and demanded an immediate end to the use of force against them.
Damascus has ignored growing Western condemnation and sanctions, determined to crush the pro-democracy revolt by sending out security forces and tanks to subdue unrest it blames on armed groups who are backed by foreign powers.
Human rights activists said protests flared on Friday in the eastern cities of Deir al-Zor and Albu Kamal, where people burned pictures of Lebanese Hezbollah leader Hassan Nasrallah, who this week threw his weight behind the authoritarian Assad.
Residents said security forces fired shots at protesters in Deir al-Zor. State television said "armed elements" opened fire on security troops in Deir al-Zor and five of them were wounded.
There was no word of any casualties among protesters.
Witness reports of events are hard to verify independently because Assad's government has barred most foreign media from the country not long after the unrest erupted, emboldened
by democratic revolutions in Egypt and Tunisia.
Residents said gunfire was also heard in the central city of Homs as thousands gathered despite a heavy security presence, while five protesters were wounded by security forces' shooting in Zabadani, a western town near the Lebanese border.
The biggest demonstrations typically occur on Fridays after Muslim prayers, and they have also generally been the deadliest. Lately, protesters have taken to holding nightly demonstrations in an attempt to circumvent a heavy security presence.
Two witnesses said security forces fired live rounds on Thursday at hundreds of protesters in a night rally in Deraa. In the nearby town of Dael, residents said security forces shot
dead three demonstrators on Thursday night.
Thousands of people in Dael and other cities across Syria stood on rooftops and balconies and chanted the Muslim rallying cry "Allahu Akbar" (God is greatest) until dawn on Friday in a show of defiance, activists and witnesses said.
"The chants mixed with the sounds of bullets," said one of the residents, who gave his name as Abu Hamed.
"Path of dialogue"
In a communique to be issued later after a two-day G8 summit held in Deauville, France, the leaders of the seven Western powers plus Russia called on Damascus to respond to the Syrian people's "legitimate demands for freedom".
"We are appalled by the deaths of many peaceful protesters as a result of the sweeping use of violence in Syria as well as by repeated and serious violations of human rights," the leaders said in a communique.
"Only the path of dialogue and fundamental reforms will lead to democracy and thus to long-term security and prosperity in Syria. Should the Syrian authorities not heed this call, we will consider further measures," the draft said.
The United States and European Union have already imposed sanctions against Assad and other Syrian officials, which Damascus roundly condemned. But Russia has been more reticent in denouncing Assad because of a desire to reassert old Soviet-era influence in the region.
Nevertheless, despite the initial negative reactions from Moscow and Beijing, Western diplomats have said they hope both nations will not block a draft resolution which Britain, France, Germany and Portugal circulated to the UN Security Council on Wednesday.
The draft says Syria's actions may amount to crimes against humanity and it "condemns the systematic violation of human rights, including the killings, arbitrary detentions, disappearances, and torture of peaceful demonstrators, human rights defenders and journalists".
Assad, who inherited power from his father Hafez Assad on his death in 2000, has pledged to launch a national dialogue and undertake some reforms in the Sunni Muslim-majority country that has been in the grip of his minority Alawite sect for 48 years.
But protesters and activists have dismissed the moves as empty gestures since the security forces have continued to violently suppress protesters.
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