U.S.-allied forces take Syria's largest oil field from ISIS

U.S.-allied forces said Sunday they have captured Syria's largest oil field from the group Islamic State in Iraq and Syria (ISIS).

The Kurdish-led Syrian Democratic Forces, who are in a race with Russian-backed Syrian troops to seize parts of the oil-rich Deir el-Zour province, said they are in full control of the Al-Omar field.

The SDF has already driven ISIS from Deir el-Zour's main natural gas field and smaller oil fields. It says government forces are three kilometres away from the fields.

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The Syrian Observatory for Human Rights says pro-government forces retreated from the area around Al-Omar field after coming under heavy fire from ISIS militants. Earlier this month, pro-government forces seized the town of Mayadeen, just across the Euphrates River.

ISIS captured Al-Omar in 2014, when the group swept across large areas in Syria and neighbouring Iraq. The field was estimated to produce around 9,000 barrels a day, making it a key source of revenue for the extremists. Its current potential is unknown, following a series of strikes on IS-held oil facilities by the U.S.-led coalition.

Al-Manar TV, operated by Hezbollah, said the fight for Al-Omar was still underway and denied the SDF's claim to have captured it. The Lebanese militant group is fighting alongside Syrian President Bashar Assad's forces.

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ISIS has suffered a series of major setbacks in recent months, including the loss of the Syrian city of Raqqa, once the extremists' self-styled capital, and the Iraqi city of Mosul. Most of the territory the group once held has been seized by an array of Syrian and Iraqi forces.