At least 10 jihadist fighters were killed in airstrikes in northern Syria's Idlib province on Wednesday, the latest in a series of strikes targeting al-Qaeda-linked militants, a monitoring group said.
Unidentified aircraft hit two cars and three motorbikes near the town of Saraqeb south of Aleppo, the Syrian Observatory for Human Rights said.
The Britain-based monitoring group said it was not clear whether all the dead were members of the al-Qaeda-linked Fath al-Sham Front or whether some of them belonged to smaller jihadist groups.
Media activists close to the Syrian opposition put the number of dead at 15 Fath al-Sham Front members, including two of the group's leaders.
An uptick in airstrikes in recent weeks is thought to have been carried out by the US-led coalition against Islamic State and other extremist groups, targeting Fath al-Sham and allied groups.
"Clearly, the US or closely allied intelligence agencies have infiltrated JFS/AQ in #Syria at its highest levels and ... are increasingly capable of precisely locating senior leadership figures for targeted strikes," analyst Charles Lister of the Middle East Institute commented in a Facebook post after strikes last week.
Fath al-Sham, along with hardline Islamist group Ahrar al-Sham, dominates Idlib province, the largest remaining rebel-held territory in Syria.
Under its former name of al-Nusra Front, the group was the official Syrian affiliate of the al-Qaeda international jihadist network founded by Osama bin Laden.
Fath al-Sham and sympathetic clerics are currently calling for a major merger of Islamist rebel groups, but other rebels are pushing for a rival unity project that would exclude the jihadists and help rebels maintain links with sympathetic Western and Gulf states.
Meanwhile, Syrian opposition politicians and rebel leaders were meeting in Ankara to discuss their position on Turkish- and Russian-brokered peace talks due to take place later this month in the Kazakh capital Astana.
Members of groups aligned to Turkey were attending the meeting, opposition politician Samir al-Nashar, who was not taking part, told dpa.
Turkey, a key rebel backer, has grown closer to Syrian government ally Russia in recent months.
Simultaneously, it has shifted its focus from regime change to wresting control of areas near its border from Islamic State and US-allied Kurdish forces.
Rebels have expressed doubts about the Astana talks and a ceasefire due to ongoing fighting, especially in the Barada valley near Damascus where government forces are seeking to regain control of the sources of the capital's water supply.
A spokesman for Syria's dominant Kurdish party, whose allied militias are the main US ally on the ground against Islamic State, told dpa that his group had not been invited to the Astana talks.
"If our Kurdish party is not invited we will not abide by anything that comes out of this meeting," Ibrahim Ibrahim of the Democratic Union Party (PYD) said.
The PYD-aligned, Kurdish-led Syrian Democratic Forces control much of northern Syria after a successful US-backed campaign against Islamic State. They are now pressing towards the jihadists' de facto Syrian capital, al-Raqqa.
However, both the Syrian government and rebels reject their aspirations for autonomy in a confederal Syria.