Rebels launched deadly attacks on Syria's military Saturday in a campaign increasingly targeting its air power, as Russia said it was "naive" to expect its traditional ally not to fight back.
Opposition forces captured the main air defence building in Albu Kamal on the Iraqi border, the Syrian Observatory for Human Rights said, adding reports suggested they had seized ground-to-air missiles.
The assault late Friday came hot on the heels of a rebel attack on the Abu Zohur air base in Idlib province in the northwest, where the Free Syrian Army said it downed a MiG warplane this week.
Mi-17 and Mi-24 helicopter gunships overflew Taftanaz throughout Saturday, as rebels in the Idlib provincial town took shelter inside houses, an AFP correspondent reported.
Taftanaz is just two kilometres (just over a mile) from a major base from where helicopters take off round the clock to pound opposition-held areas. Rebels attacked the base on Wednesday but failed to take control of it.
"The attack on the airport was a failure, it wasn't well prepared," admitted Abu Omar, who said one helicopter was destroyed and others damaged.
"The operation was carried out by the Ahrar al-Sham Brigade who arrived here at dawn," the rebel commander told AFP. "There was no real preparation. I refused to take part."
Though large swathes of the countryside are in rebel hands, the regime still controls Idlib city.
In their assault in Albu Kamal, rebels also captured 16 air defence personnel and attacked nearby Hamdan air base, the Observatory said.
The seizure was a "major coup" for the rebels, the watchdog's head Rami Abdel Rahman said, adding it sparked retaliatory shelling in the town of some 60,000 that killed at least five civilians.
They were among 125 people killed in nationwide violence on Friday, including 74 civilians, 29 soldiers and 22 rebels, said the Observatory, making August the deadliest month of the conflict so far with nearly 5,000 dead.
The rebels claim to have shot down a MiG fighter and destroyed a dozen aircraft on the ground in their attacks on air bases in the past week as they seek to curb the government's use of warplanes and helicopter gunships.
State media, meanwhile, reported a "terrorist" group had killed five members of a family in the central Marjeh district of Syria's second city Aleppo, a key battleground in the more than 17-month-long conflict.
In the central province of Hama, rebels killed at least four soldiers in a roadblock attack, the Observatory said.
It also said 18 unidentified bodies were found in the Damascus area on Saturday, most with their hands tied and some bearing signs of torture.
The army also pounded several towns east of Damascus, including Douma -- scene of frequent bloodshed -- and Irbid, said the Observatory.
Both Damascus and Aleppo have seen persistent fighting between troops and rebels in a conflict that has now claimed more than 26,000 lives since March 2011, according to the Observatory.
At least 60 people, mostly civilians, were killed countrywide on Saturday, said the Britain-based monitoring group.
The official SANA news agency said 225 prisoners "implicated in recent events but without blood on their hands" were freed in Damascus province on Saturday.
As they emerged from police headquarters, several of those being released had nothing on but their underwear, while some still bore tell-tale marks of beatings, an AFP correspondent in the capital reported.
"With our blood and with our souls, we will defend you, O Bashar!" they chanted, clapping in unison.
In talks with Syrian Prime Minister Wael al-Halaqi in Tehran on Friday, UN chief Ban Ki-moon said the regime of President Bashar al-Assad must stop using its heavy weapons.
But Russian Foreign Minister Sergei Lavrov said Western and Arab calls for the government to unilaterally withdraw its troops amounted to a demand for "capitulation" they had no right to make.
"When our partners say that the government must stop first and withdraw all its soldiers and weapons from cities -- and only then call on the opposition to do the same -- well, this is a completely unworkable scheme," said Lavrov.
"Either people are naive or it is some sort of provocation," he added.
Lavrov stressed that Moscow, a Cold War era ally of Damascus, was not trying to support Assad or his government but was basing its policies on the daily situation on the ground.
Veteran troubleshooter Lakhdar Brahimi has now taken up faltering international attempts to end the conflict but with low expectations that he will have any more success than his predecessor, former UN leader Kofi Annan.
In an interview with Al-Arabiya television, Brahimi urged "all parties to stop the violence," adding that "the government assumes greater responsibility" for the cessation of hostilities.
The call came ahead of meetings that the former Algerian foreign minister was to hold on Saturday at UN headquarters.