Syrian security forces on Friday pressed a months-long crackdown on dissent, killing six more people with gunfire as protesters flooded streets in support of a rebel army, activists said.
The latest violence came as an Arab League 1100 GMT deadline for Syria to accept an observers' mission or face sanctions passed with no response from Damascus.
The Syrian Observatory for Human Rights said at least six people were killed when security forces opened fire on demonstrators at various flashpoints in the south, centre and east of the country.
It said three people were killed, including a 19-year-old man, in central Homs province when security forces opened fire near a mosque, while a 16-year-old was shot dead in the southern Daraa province, cradle of eight months of dissent, the Observatory said.
Another man was killed in the eastern city of Deir Ezzor and a sixth near Damascus, according to the rights watchdog.
Internet activists had called for a day of massive protests nationwide in support of the rebel Syrian Free Army (SFA) which has stepped up attacks in a bid to topple the regime.
"The Free Army is the guardian of our peaceful revolution," anti-regime activists said on their Facebook site Syria Revolution 2011.
Like most Fridays since the start of the pro-democracy movement in mid-March, protesters emerged from midday prayers to face security forces who bolstered their deployment at key centres of dissent.
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State television denied there a death in Deir Ezzor.
The official SANA news agency, meanwhile, reported that two experts were killed trying to defuse a bomb in the restive city of Hama, in central Syria, accusing "armed terrorist groups" of planting the device.
The state-run agency, quoting a police source, said three other bombs exploded in Hama.
And the military confirmed that six elite pilots and four others were killed in an attack on Thursday, accusing foreign powers of supporting acts of terror within Syria.
"An armed terrorist gang murdered six pilots, an officer and three junior officers working for the military airbase," the army said in a statement quoted by SANA.
The ambush "took place on the Palmyra-Homs road yesterday afternoon."
The attack was claimed on Thursday by the rebel Free Syrian Army who said seven military pilots were killed in an ambush on a bus.
According to the Observatory, huge protests took place across Idlib on Friday, mainly in Maaret Noman where demonstrators called for the "fall of the regime."
But SANA said massive counter-rallies were held in Damascus and Syria's second city Aleppo, with protesters denouncing Arab League decisions against Syria and vowing to confront "the conspiracy" facing their nation.