U.S.-backed Syrian militias said they seized a major dam on the Euphrates river from Islamic State on Sunday, their latest gain as they push toward Raqqa city.

The Syrian Democratic Forces, an alliance of Kurdish and Arab fighters, said they captured the Baath Dam in the morning, renaming it Freedom Dam. The hydroelectric facility lies 22 km upstream of Raqqa, where Islamic State's operations in Syria are based.

The spokesman for the Kurdish YPG militia, the SDF's key component, said fighters were combing nearby villages for mines and shoring up their defensive lines. "The dam has been completely liberated," Nouri Mahmoud said.