DAMASCUS/BEIRUT: Syrian rebel military gains outpaced diplomacy again Friday, when opposition forces overran a strategic northern government air base, and talks on ending the civil war failed to make headway in Geneva.

Rebels overran the Taftanaz air base in the northern Idlib province, activists said, in a significant advance after a weekslong siege.

Three-way talks between the U.N. peace envoy and officials from opposing superpowers on the conflict – the U.S. and Russia – in Geneva concluded with no apparent political breakthrough.

“The fighting at Taftanaz military airport ended at 11 a.m. and the base is entirely in rebel hands,” said head of the opposition activist network the Syrian Observatory for Human Rights director Rami Abdelrahman.

Soon afterward, however, it was raided by government jets, the Britain-based Observatory said. “Warplanes are bombing Taftanaz military airport in an attempt to destroy it,” a statement said.

The Taftanaz air base in Idlib province is the largest air base yet to be captured by the rebels, and it is the biggest field in the north of the country for the helicopters that the regime has used to bomb rebel-held areas and deliver supplies to government troops.

The capture further chips away at the regime’s airpower in the north, which Damascus has relied upon increasingly over the past year as it lost control of large swaths of territory.

But it doesn’t eliminate the threat to rebels from the air. There remain several other, smaller helicopter bases, and regime warplanes that also strike the area operate from bases further south. The capture wouldn’t affect the military’s airpower against rebels in other parts of the country.

But the fall of the base is a sign of its fraying hold in the north. It also provides a strong boost for the arsenal of the rebels, who partially rely on weapons looted from the military.

Rebels from Al-Qaeda-affiliated Nusra Front and several other, mainly Islamist brigades have been fighting for weeks for control of the sprawling Taftanaz facility and broke into it Wednesday evening. Activists said the rebels seized control of buildings, ammunition and military equipment after ferocious fighting at dawn.

“As of now, the rebels are in full control of the air base,” said Idlib-based activist Mohammad Kanaan. He acknowledged that government airstrikes will not stop, but said the base’s fall puts “another big nail in the coffin of the regime.”

A video taken by activists inside the base and posted online showed helicopters in the field, some of which appeared intact while others were destroyed.

“These are the helicopters that belonged to Assad’s regime and now they are the helicopters of the Syrian people,” said the narrator as he reached a parked helicopter that looked intact.

The video showed rebels dismantling ammunition from a heavy machine gun in the base and loading the ammunition into a truck. In other videos, rebels are seen celebrating inside the base, some kneeling and kissing the ground and others showing off booty including multiple rocket launchers.

The videos appeared genuine and corresponded to other reporting on the events depicted.

The weaponry at the bases is a key prize for the rebels, though it is not clear whether they can use the helicopters themselves. Rebels have captured helicopters in the past but there’s been no reported case of them flying one.

Kanaan, the activist in Idlib, said the rebels seized tanks and helicopters at the base, but added that most if not all of the helicopters were damaged from the fighting and were nonfunctional. The Observatory said around 20 helicopters were seized but none were in working order.

In one video, at least six dead men in military uniform were seen on the ground outside one of the housing units in the base. Two other dead men were seen inside the building. “They refused to defect. We have been urging them to defect since our attack began 10 days ago,” the rebel narrating the video said.

There was no immediate word on casualties.

The rebels had been attacking Taftanaz for months, launching a fresh offensive on it in early November with a force activists estimated at about 700 fighters.

The assault was also a sign of the strength of Islamic hard-liners within the rebel ranks. The fighters included members of the Nusra Front, a group affiliated with Al-Qaeda that includes many foreign fighters, along with Ahrar al-Sham, a group with a similar ideology. Fighters from the Nusra Front, which the U.S. has branded a terrorist organization, have been among the most effective in the rebels’ battle to oust Assad.

Last week, the rebels began major attacks on three other air bases in Idlib and the nearby province of Aleppo.

Taftanaz lies near the highway between the capital Damascus and the northern city of Aleppo, a major front in the civil war that has stood at a stalemate for months.

But it is unclear whether the rebels will try to retain control of Taftanaz. The opposition has seized several other air defense bases, making off with weapons and ammunition, but in most cases has not managed to retain the facilities.

The rebel military gains came as U.N.-Arab League special envoy on Syria Lakhdar Brahimi met Russian Deputy Foreign Minister Mikhail Bogdanov and U.S. Undersecretary of State William Burns.

After more than five hours of talks, Brahimi expressed an urgent need to end the conflict, but reported no major progress.

“We all stressed the need for a speedy end to the bloodshed and the destruction and all forms of violence in Syria,” he told reporters.

The discussions took place a day after Syria accused Brahimi of “flagrant bias,” casting doubt on his mediation.

Damascus lashed out at the veteran Algerian diplomat after he described as “one-sided” proposals Assad made Sunday for a “political solution.”

In comments to the BBC, Brahimi attacked Assad’s plan to keep fighting rebel “terrorists” and ignore opposition groups tied to them.

He also questioned the decadeslong rule by Assad’s family.

There had been some hope that Friday’s talks could produce a clearer idea of how to move toward a transitional government in Syria, where the U.N. estimates more than 60,000 people have died since the March 2011 outbreak of the revolt.

Despite wintry conditions, thousands of Syrians staged nationwide demonstrations Friday denouncing “death camps” – referring to refugees suffering in tent settlements in neighboring states, which this week were hit by storms.

The U.N. said 612,134 Syrians had been registered as refugees in the region or were in the process of being registered.

“They left with their wives and children fearing kidnappings, bombings and snipers. They dreamed of a tent safely away from the gangs of Assad, but instead were met with a slow death,” activists wrote on the Facebook page Syrian Revolution 2011.