Turkish President Recep Tayyip Erdogan on Wednesday strongly condemned Russia for conducting an air strike that killed dozens of pro-Ankara rebels in Syria.

Clashes Tuesday in the Syrian desert between Russia-backed regime forces and Islamic State group jihadists have killed almost 30 fighters, a Britain-based war monitor said.

Air strikes by Damascus regime ally Russia killed 78 Turkey-backed rebels in northwestern Syria on Monday, a monitor said, in the bloodiest surge in violence since a truce almost eight months ago.

More than 90 others were wounded when Russian warplanes targeted a training camp of the Faylaq al-Sham faction in the Jabal Duwayli area in Idlib province, the Syrian Observatory for Human Rights said.

Clutching a small saw, Syrian volunteer Rana Jreij cut away at bushes growing up the centuries-old walls of one of the world's most famous Crusader castles, Krak des Chevaliers.

The man who decapitated a teacher in France for showing cartoons of the Prophet Mohammed in class had been in contact with a Russian-speaking jihadist in Syria, a source close to the case said on Thursday.

Seven people have been charged with complicity after 18-year-old Chechen Abdullakh Anzorov killed Samuel Paty on Friday, including two teenagers who helped him identify the teacher.

Damascus has sharply increased petrol prices in government-held areas of Syria, saying that US sanctions on the war-torn country had left it with no alternative.

An Israeli strike hit the province of Quneitra in southern Syria, state media reported on Wednesday.

Attacks on civilian targets during a Syrian-Russian campaign in northeast Syria's rebel-held Idlib may amount to crimes against humanity, Human Rights Watch said Thursday, calling for sanctions against top commanders.

Clashes in the Syrian Desert between pro-government forces and holdouts of the Islamic State group have killed at least 90 combatants this month, a war monitor said on Wednesday. 

Desperate to help his family displaced by Syria's war, pro-Turkey rebel fighter Abu Ahmad is waiting to be deployed to Azerbaijan hoping to earn almost 80 times his current salary.