A senior commander of the Syrian militant group formerly known as al-Nusra Front has been killed near Aleppo, rebel sources say.
The group Jabhat Fateh al-Sham said on its Twitter account that commander Abu Omar Sarakeb died in an air strike in Aleppo province.
It did not say which country’s forces had carried out the air strike.
Al-Nusra Front changed its name at the end of July, reportedly cutting ties with al-Qaeda at the same time.
The Syrian government, Russia and a US-led coalition have all been carrying out air strikes against militant groups in Syria.
A source quoted by Reuters said that Abu Omar Sarakeb and others had been targeted in a hideout in the village of Kafr Naha, west of Aleppo city.
Unconfirmed reports said several other senior figures in the group were killed or injured, Reuters reported.
The Syrian Observatory for Human rights, a UK-based group which draws its information from activists on the ground, said an air strike from unknown warplanes had hit a meeting of Jabhat Fateh al-Sham, killing Sarakeb and another military commander named as Abu Muslem al-Shami.
Al-Nusra was excluded from February’s cessation of hostilities agreement in Syria along with so-called Islamic State (IS).
Despite its new name, the US said it saw no reason to change its view of the group as a terrorist organisation.
The embattled city of Aleppo and surrounding districts have seen some of the fiercest clashes in Syria’s civil war in recent months.
Diplomatic efforts to end the fighting have so far come to nothing.
US Secretary of State John Kerry is due to hold talks on Syria with Russian Foreign Secretary Sergei Lavrov in Geneva on Friday.
It is understood they will discuss efforts to forge a nationwide truce, improve humanitarian aid deliveries and restart peace talks.
Russia is a key ally of Syrian President Bashar al-Assad.
Syria was also discussed on Thursday in a phone call between Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan, Turkish state media reported.
Mr Erdogan told Mr Putin that a ceasefire in Aleppo was needed “as soon as possible,” Anadolu news agency reported.
Meanwhile, CIA director John Brennan has warned that IS fighters will remain a threat to the West for “a number of years to come” even if the group is defeated in Syria and Iraq.
“You have a lot of these foreign fighters who have come into the theatre that will either stay and fight, and die trying, or they will try to return to their home countries,” he told a conference in the US.
“Some of them may be rehabilitated and some of them may see that they were on the wrong path, but I think a number of them are going to remain a challenge for the United States and other governments for a number of years to come.”
US Defence Secretary Ash Carter, speaking in the UK on Thursday, said he was confident that IS would be pushed back into its strongholds of Raqqa, in Syria, and Mosul, in Iraq, within months, before being militarily defeated.