An air strike late on Tuesday hit fuel tankers in Syrian territory shortly after they entered from Iraq, killing about 15 people, the UK-based Syrian Observatory for Human Rights said.
The strike hit two of the eight tankers that entered from Al Qaim border crossing in western Iraq to Albu Kamal in Syria, a senior Iraqi official told The National.
The vehicles were part of a 22-tanker convoy transporting fuel oil from Iran to Lebanon, he said. The convoy entered Iraq and then Syria legally in co-ordination between the governments.
It is not clear whether the attack was carried out by a drone or fighter jet and there were no further details of those killed or injured..
The strike hit a convoy of "fuel tankers and trucks loaded with weapons", the Observatory said. Most of those killed were militiamen, according to the monitor.
Iraq and Iran have been supplying Lebanon with fuel oil to alleviate pressure on the country's struggling electricity grid.
The Iraqi-Syrian border area has been the site of several air strikes against Iran-backed militias.
The militias established a foothold in Syria while fighting in support of President Bashar Al Assad during the civil war that began in 2011. The war against ISIS between 2014 and 2017 bolstered their positions.
They have since turned their attention to smuggling weapons into the country, including missile systems that could be used against Israel.
They accuse the US and Israel of carrying out these attacks.
