A bomb blast on Tuesday near a key in the east Syria He attacked US-backed fighters but killed three workers, a war monitor said Tuesday.
The Syria n Observatory for Human Rights said the explosion occurred on the road outside the Al-Omar oilfield, the country’s largest in the eastern province of Deir Ezzor.
Al-Omar is under the control of those backed by the United States who have been fighting the Islamic State group.
Part of the oil field is used as an SDF base, while workers have resumed production in another.
The explosion on Tuesday struck the nearby road when a vehicle carrying oilfield employees passed, killing three workers, said Observatory chief Rami Abdel Rahman.
The explosive device was detonated some distance just after an SDF patrol passed, said the head of the British-based monitoring group.
There was no immediate claim for the explosion, but IS often says it is responsible for the deadly attacks in the area.
The Kurd-led SDF expelled the Islamic State from its last patch of territory in the village of Baghouz, south of Al-Omar, in March, but has continued to sweep the jihadist sleeping cells.
IS overran large parts of Syria and neighbouring Iraq in 2014, declaring a caliphate and implementing its brutal interpretation of Islam in millions.
The jihadists took Al-Omar that same year, before the SDF regained control a little more than a year later with the support of the air attacks of a US-led coalition.
The air strikes in 2015 destroyed the field, after the jihadists earned estimated oil revenues of between $ 1.7 million and USD 5.1 million a month, according to the coalition.
Syria ‘s eight-year war has killed more than 370,000 people and displaced millions since it started in 2011 with the brutal repression of anti-government protests.
The conflict has seen the Damascus regime lose control of key oil fields and has caused state revenues from hydrocarbons to drop by billions of dollars.