Deserters killed eight soldiers and members of the security forces and wounded 40 more in an attack on Saturday in Idlib in northwest Syria, the Syrian Observatory for Human Rights said.
"A group of deserters attacked a squad of soldiers and security agents in a convoy of seven vehicles, including three all-terrain vehicles, on the road from Ghadka to Maaret Numan," the Britain-based watchdog said.
"Eight were killed and at least 40 more were wounded. The deserters were able to withdraw without suffering any casualties," it added.
Earlier, the same group said at least 10 members of the security forces were killed in clashes with mutinous soldiers in Deir Ezzor in the east on Friday.
It also said five civilians including a child were shot dead on Saturday in central and eastern Syria.
Four civilians including the child died when hit by gunfire in the central Homs region and a fifth was killed as security forces launched raids in Deir Ezzor and carried out arrests, it said.
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In a new toll, the activists said at least 16 people were killed on Friday as protesters flooded the streets in support of the Free Syrian Army.
On Friday, the military confirmed that six elite pilots and four others were killed in an attack the previous day, 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 air base" on Thursday, the army said in a statement quoted by the state news agency SANA.
The ambush "took place on the Palmyra-Homs road," it said.
Thursday's attack was claimed by the rebel Free Syrian Army who said seven military pilots were killed in an ambush on a bus.
The rebel army has stepped up attacks on regime targets in recent weeks in a bid to topple the government of President Bashar al-Assad who has waged a bloody crackdown on pro-democracy protesters since mid-March.
The latest violence came as Arab ministers gathered in Cairo to draw up a package of crippling sanctions against Syria after Assad's regime ignored a Friday deadline to accept an observers' mission to monitor the violence.