A woman walks as she is holding new stuff she bought in Deir al-Zour city in eastern Syria, Sept.11, 2017. Food and medical aid started entering Deir al-Zour city, days after the Syrian army lifted the Islamic State (IS) siege on the city, where 93,000 civilians have been besieged for three years. (Xinhua Photo)

DAMASCUS, Oct. 22 (Xinhua) -- The U.S.-backed Syrian Democratic Forces (SDF) said Sunday that they have captured the al-Omar oil field, one of the largest energy fields in Syria.

Located in the eastern countryside of Deir al-Zour province in eastern Syria, the SDF said it captured it from the Islamic State (IS) and kept the Syrian government forces three kilometers away.

A day earlier, some reports emerged about the Syrian forces' control over the oil field, but sources in Deir al-Zour said the field was still under IS control until the SDF declared capturing the facility on Sunday.

Al-Omar field produces 30,000 oil barrels per day and contains a gas factory and electricity-generating station.

The SDF fighters are now concentrating their operations in Deir al-Zour, just days after fully capturing the northern province of Raqqa, which was the de facto capital of IS.

The Syrian army is also advancing in Deir al-Zour, capturing over 90 percent of the capital city there, and advancing in the countryside.

Still, the SDF control over the field may trigger some tension with the Syrian army, which was advancing toward the field after capturing the city of Mayadeen, deemed as the capital of IS in Deir al-Zour.