“Our frontline forces against IS and coalition forces in the area of the Omar oil field dealt with drone attacks,” the Kurdish-led Syrian Democratic Forces (SDF) said. They said initial reports indicated the attacks had caused no damage.

It was the second such attempted attack in days after the SDF reported “two unidentified rocket-propelled grenades landed on the western side of the al-Omar oil field” late Sunday, without causing casualties.

The Syrian Observatory for Human Rights, a Britain-based war monitor with sources inside Syria, said some Iraqi militias had probably launched the drones from a rural area outside the town of Al-Mayadeen southwest of the oil field.

The failed drone attacks came as a coalition spokesman said 14 rockets were fired at the Ain al-Assad airbase which hosts American troops in neighboring Iraq.

The Iraqi militias also fired several shells at Al-Omar on Monday last week, causing damage but no casualties, the Observatory said.

The shelling came after the US launched airstrikes the previous night against three targets it said were used by some groups in eastern Syria and western Iraq.

Reporter's code: 50101