A senior Tunisian Islamic State leader and five other foreign jihadists were killed in an air strike near the northeastern Syrian city of Hasaka, a UK-based group monitoring the war said on Monday.
The six militants died when fighter jets targeted the car they were travelling in on the southern outskirts of Hasaka, said the Syrian Observatory for Human Rights.
It was not clear whether the air strike was carried out by the Syrian army or a US-led coalition that is mounting a separate aerial campaign against Islamic State in Syria and Iraq, the monitoring group said.
The Syrian Observatory for Human Rights gets its information from a network of activists and doctors on the ground.
United States said earlier in July it had stepped up an aerial campaign against Islamic State in Syria, while the Syrian army and allied militia are battling IS in the northeast near the border with Turkey and Iraq.