Syrian rebels on Sunday captured army checkpoints near Nayrab military airport in the northern city of Aleppo, in the eastern province of Deir Ezzor and in central Hama province, a watchdog said.
In Aleppo, fierce clashes took place between Syrian troops and several rebel battalions, which resulted in the insurgents taking over the checkpoint near Nayrab airport, the Syrian Observatory for Human Rights said.
Nayrab is adjacent to Aleppo international airport, a key target for the rebels, who have also been battling troops guarding Kweyris military airbase east of the city and Menegh airbase to the north.
The Observatory, which collects its reports from a network of activists and medics in civilian and military hospitals on the ground, said at least six soldiers and a number of rebels were killed in Sunday's fighting.
Fighter planes carried out raids on rebel groups encircling the military defense factories in the town of Safireh east of Aleppo.
In the eastern province of Deir Ezzor, rebels lost five men before capturing the Kibar checkpoint, seizing stores of weapons and ammunition and killing at least four soldiers, the watchdog said.
The districts of Sheikh Yassin and Hamidiyeh in the embattled city of Deir Ezzor came under army bombardment as warplanes circled overhead.
In the central province of Hama, the rebels lost one of their commanders when they took control of a military checkpoint near the town of Qalaa al-Maziq, where heavy regime shelling killed three people, including a child.
The Observatory also reported that five soldiers were killed defending Tel Osman checkpoint before it fell to the insurgents.
East of Qalaa al-Maziq, regime forces stormed the town of Mork, which has seen several rounds of fighting, with advancing troops being pushed back by the rebels, and then entering again, the watchdog said.
Mork is located on the highway connecting Hama to the strategic northwestern city of Maaret al-Numan, whose capture by the insurgents last October has hampered army supply lines to Aleppo further north.
Regime forces are pushing to take back the strategic stretch of road.
The Observatory gave an initial toll of 42 people killed on Sunday in Syria, where the UN estimates that nearly 70,000 people have died since the outbreak of the uprising in March 2011.