BEIRUT -- Airstrikes on Syria’s rebel-held Idlib province killed at least 11 people on Monday, opposition activists said, in the latest spasm of violence to mar U.N.-brokered talks in Geneva between the government and the opposition.

Separately, there were unconfirmed reports that a top al-Qaeda official was killed in an airstrike, also in Idlib.

Also on Monday, pro-government forces drove Islamic State of Iraq and Syria (ISIS) militants out of a line of villages in the congested Turkish frontier region, blocking the path of rival Turkish-backed opposition forces from reaching the de facto ISIS capital, Raqqa, opposition activists said.

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The SITE Intelligence Group, which monitors extremist groups, said Abdullah Muhammad Rajab Abdulrahman, the deputy to al-Qaeda leader Ayman al-Zawahiri, may have been killed in a U.S. airstrike on an unmarked sedan on Sunday evening. It cited reports circulating on jihadi social media accounts.

The northwestern province falls largely under the control of an al-Qaida-linked rebel coalition. Hundreds of thousands of Syrians displaced by fighting are living as refugees there.

Images of the vehicle purported to have been carrying Abdulrahman, known more widely by his nom de guerre Abu al-Khayr al-Masri, showed damage to the passenger compartment of the beige Kia sedan but no damage to the engine block. The roof was blown open on the right side of the vehicle.

The Britain-based Syrian Observatory for Human Rights reported that a top al-Qaida official was killed in a drone strike, but could not confirm it was al-Masri.

Al-Masri was a close associate of Osama Bin Laden and was once the chairman of al-Qaida’s management council, according to a Washington Post report citing leaked US intelligence documents dating back to 2008.

Iranian authorities are believed to have jailed him following the 9/11 attacks before releasing him in a prisoner exchange with al-Qaida in Yemen in 2015.

A senior official in a rival jihadi faction in northern Syria urged caution over the reports, saying other top al-Qaida officials in Syria had staged their own deaths only to defect from the group. The official asked not to be identified because of rivalries between the various factions.

There was no immediate comment from the Pentagon.

Government forces and allied Hezbollah fighters meanwhile cut an arc through ISIS-held territory to reach independent, Kurdish-led forces near the Euphrates River, effectively preventing Turkish-backed Syrian opposition forces from heading south toward Raqqa.

The opposition forces, which seized al-Bab from the ISIS group last week, will now have to confront government forces or the rival Kurdish forces if they desire to reach Raqqa, which is further southwest along the Euphrates River.

Those forces are accompanied by a deployment of Turkish troops, tanks and artillery inside Syrian territory. Turkey says the nearby Kurdish-led forces are terrorists.

The opposition accused the government of setting up a buffer zone between opposition fighters and ISIS.

“The Syrian regime claims it is fighting terrorism but it is not. It cut the path for the Free Syrian Army factions to reach Raqqa,” said Col. Abu Firas, a spokesman for the Free Syrian Army, a loose alliance of mainstream rebels.

The government “claims it wants to fight terrorism but in reality it wants terrorism to stay put, because an end to terrorism would mean the end of regime,” he told The Associated Press.

He spoke after an opposition delegation met Monday with U.N. mediator Staffan de Mistura to continue talks aimed at resolving Syria’s six-year-old war. The talks, which began last week, have so far been stuck on the agenda.

The government insists the talks should start with an agreement on the need to fight terrorism, while the opposition wants to discuss a political transition.

Civil defense members try to put out a fire at a site hit by airstrikes in the rebel-controlled town of Ariha in Idlib province, Syria Feb. 25, 2017. REUTERS/Ammar Abdullah

Abu Mohammed al-Golani, leader of the al-Qaida-affiliated Fatah al-Sham Front, criticized the Syrian politicians and rebels taking part in the talks, saying they “were handing victory” to Assad. His group is a coalition of ultra-conservative insurgent factions.

Back in Idlib, the activist-run Baladi News network published footage of rescuers searching for victims in the rubble of a block destroyed in presumed government or Russian airstrikes on Monday, in the town of Areeha.

The Syrian Civil Defense search-and-rescue group said it had counted 15 fatalities.

The Britain-based Syrian Observatory for Human Rights said at least seven civilians and four other unidentified victims had been killed. It blamed the attack on government warplanes.