An unidentified drone strike in northwest Syria killed 14 jihadists including five foreigners and six commanders near the border Thursday, the Syrian Observatory for Human Rights said.

The strike targeted a dinner meeting of jihadists in the village of Jakara in the area of Salqin, the Britain-based war monitor said. It was not immediately clear who was behind the attack.

The strike hit in Syria's last major rebel bastion of Idlib, which is dominated by the Hayat Tahrir al-Sham (HTS) group led a former Al-Qaeda affiliate, but other jihadist groups are also present in the area.

Observatory chief Rami Abdel Rahman said that five non-Syrian jihadists were among those killed, but their nationalities were not immediately known. Among the six Syrian leaders killed, two were from HTS, he said. Ebaa, the media mouthpiece of HTS, said a strike targeted a "tent belonging to one of the dignitaries" in Jakara, killing several people.

A US-led coalition is present in the east of the country, where its airstrikes have backed Kurdish-led forces battling the Islamic State group. Thursday's strike came after it emerged that the 18-year-old who killed a school teacher in France last week for showing cartoons of the Prophet Mohammed in the class had been in contact with a Russian-speaking jihadist in Syria.

But the source close to the case said the identity of the Russian-speaking jihadist was not yet known. After a string of military victories backed by key ally Russia, the Syrian government has regained control of around 70 per cent of the country, the Observatory says.

Syria's war has killed more than 380,000 people and displaced millions from their homes since starting in 2011 with the repression of anti-government protests.

Israel has carried out hundreds of strikes in the war-torn country, but these tend to target Iranian and Lebanese Hezbollah forces as well as government troops.