Syrian state-run TV claims the leader of the powerful al-Qaida-linked Jabhat al-Nusra has been killed.
Friday's one-line report, which could not be immediately confirmed, says Abu Mohammad al-Golani was killed in the coastal province of Latakia. It did not say when or give other details. Opposition groups had no immediate comment on the report.
Hours after the report, however, AFP reported Syria state TV withdrew report claiming al-Golani was killed, and BBC reported that Syrian rebels had cast doubt on the death of al-Golani.
Rebels have gained footholds in mountainous regions of Latakia, which is largely loyal to President Bashar Atestssad.
The extremist group, also known as Nusra Front, is on a U.S. State Department list of terrorist organizations. The group has emerged as one of the most effective among rebel groups fighting Assad.
Al-Golani's death would be a huge blow to rebels who have been fragmented and outgunned by Assad's forces.
Syrian troops killed at least 40 opposition fighters in an ambush Friday near Damascus, the government said, leaving their bloodied bodies strewn on rocks near a dried-out lake along with scattered rifles and ammunition.
President Bashar Assad's forces backed by Lebanese Hezbollah gunmen also seized control of a rebel ammunition supply route on a highway linking the capital to its eastern suburbs - part of a blistering government offensive to bolster its position amid an international push for peace talks.
Assad's forces have been gaining ground in rebel-held areas around the capital, the seat of his power, and have made progress against outgunned and fragmented fighters in several areas.
On Friday, the state-run news agency SANA said 40 rebels died in the ambush near Otaiba, adding that soldiers seized a large arms cache, including anti-tank rockets.
The area is part of a region known as Eastern Ghouta, which was the scene of a horrific chemical weapons attack in August believed to have killed hundreds.
The state-run Al-Ikhbariya television station broadcast footage showing more than a dozen bodies near the largely dried-out Otaiba lake, some wearing flak jackets strapped with ammunition. Automatic rifles and hand grenades lay nearby.
"Eastern Ghouta is a graveyard of terrorists," read a scroll on the broadcast.
An unidentified Syrian army officer in the area told Al-Ikhbariya that there were foreign fighters among the dead and that the ambush followed an intelligence tip.
"It was a highly accurate operation," the officer said. "We will be moving from one victory to another."
The Britain-based Syrian Observatory for Human Rights, an activist group that tracks Syria's crisis, said at least 24 fighters, some of them foreign, were killed in the ambush. The Observatory gave no further details and the differing death tolls could not be immediately reconciled.
The offensive coincides with an international push for a peace conference to be held in Geneva. Both sides want to bolster their position on the ground ahead of the talks, expected next month. No final date has been set, however, and it is unclear whether the sides will reach an agreement on the agenda.
The Supreme Military Council, which brings together a collection of loosely-knit rebel brigades under the emblem of the Free Syrian Army, said Friday it refused to sit down with Syrian officials involved in killing Syrians. Comments carried by the Syrian National Coalition, the group's political wing, also dismissed the proposed talks for lacking a way to reach concrete results.
In other violence, a car bomb blew up near a mosque in in the village of Wadi Barada outside of Damascus shortly before Friday prayers ended. The Observatory said 40 people were either killed or wounded in the blast. SANA said the car blew up as it was being rigging with explosives. The agency said a number of people were killed.
The ambush near Damascus came hours after Assad's forces captured the town of Hatitat al-Turkomen south of the city, securing a key highway that links the capital with the Damascus International Airport. The area was scene to heavy fighting in the past.
North of Damascus, rebels and government forces clashed for a fifth consecutive day in the Christian town of Sadad, trapping hundreds of residents. Al-Qaida-linked groups captured a checkpoint earlier this week that gave them control of the western part of the town.
Archbishop Silwanos Al-Nemeh said up to 3,000 civilians were trapped amid the exchange of fire. He appealed for international organizations to help civilians flee the area.
"The situation is dire and we are worried about a massacre inside," he told The Associated Press by telephone from near Homs.
Meanwhile, Syrian helicopter gunships attacked several areas of the rebel-held northern town of Safira, southeast of the heavily contested city of Aleppo, the country's largest. A military complex near the town is believed to include an underground facility for chemical weapons production and storage.
France-based Doctors Without Borders said 130,000 people have fled Safira this month. A statement from the group said 76 people had died in the town itself.
In another development Friday, Norway turned down a U.S. request for Norwegian authorities to receive the bulk of Syria's chemical weapons for destruction, saying it doesn't have the capabilities to complete the task by the deadlines set by an international chemical watchdog.
Norwegian Foreign Minister Boerge Brende said his country could not find a port that could receive the required amount of chemical agents and didn't have the capacity to treat some of the waste products resulting from the destruction of the munitions.
The United Nations has set a mid-2014 deadline for the destruction of Syria's arsenal - a deadline Brende said was too tight for Norway.
It was unclear whether Norway's decision could delay compliance with the deadline for the destruction of weapons.
On Friday, the OPCW said its inspectors visited a site on Thursday and verified that all of its previous chemical weapons-related equipment has already been dismantled. This brings to 19 the total number of sites visited by OPCW inspectors, of 23 that have been disclosed by Syria.
The Syrian conflict has triggered a humanitarian crisis on a massive scale, killing more than 100,000 people, driving nearly 7 million more from their homes.
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