The US-led coalition destroyed three makeshift oil refineries in the Syrian territory controlled by the Takfiri militants early on Sunday.

The US-led coalition destroyed three makeshift oil refineries in the Syrian territory controlled  by the Takfiri militants early on Sunday.

The coalition strikes hit close by the Turkish frontier, near the town of Tal Abyad just across the border fence from the Turkish town of Akcakale, the “Syrian Observatory for Human Rights” said.

They came after at least a dozen strikes on Thursday night on the refinery infrastructure that the insurgents have developed in the swath of territory they control in eastern Syria, which includes many of the country's main oil fields.

"At least three makeshift refineries under ISIL control in the Tal Abyad region were destroyed overnight," the Observatory said.

"ISIL had been refining crude and selling it to Turkish buyers," said the Britain-based watchdog, whose sources are close to the foreign-backed Syrian opposition.

Before the launch of US-led air strikes on ISIL in Syria last Tuesday analysts say the Takfiri militants were earning as much as $3 million a day from oil revenues.

Output from ISIL-controlled fields stood at 80,000 barrels per day, far exceeding the 17,000 barrels per day the Syrian oil ministry said it was pumping.

The strikes around Tal Abyad came after Saturday raids on the mainly Kurdish town of Ain al-Arab, also very close to the Turkish border.

The town, known as Kobane in Kurdish, has been under assault by ISIL for more than a week, sparking an exodus of at least 160,000 refugees into Turkey.

The coalition also kept up its raids on the Insurgents’ heartland province of Raqa early Sunday as it pressed what Washington says are "near continuous" strikes.

The raids destroyed a plastics factory outside Raqa city, killing one civilian, the Observatory said.