The U.S.-backed Syrian Democratic Forces (SDF) will soon launch an offensive to oust Islamic State militants from Deir al-Zor province, an official from the alliance told Reuters on Friday.

Ahmed Abu Khawla, head of the Deir al-Zor military council which fights under the SDF, said the assault might begin “within several weeks” in parallel with the battle for Raqqa city.

The SDF alliance of Kurdish and Arab militias has been battling inside the historic Old City of Raqqa, Islamic State’s de facto capital in Syria.

Spearheaded by the Kurdish YPG militia, the SDF began its assault in June, after months of fighting to encircle Raqqa with air strikes and special forces from the U.S.-led coalition.

As Islamic State has come under pressure in Raqqa, many of its forces have fallen back on the towns and cities further east along the Euphrates in Deir al-Zor province.

“The operation to liberate Deir al-Zor will begin very, very soon,” Khawla said, adding that his unit had already “entered Deir al-Zor territory and liberated several towns” there.

Col. Ryan Dillon, a spokesman for the U.S.-led coalition, said its focus remained on Raqqa.

Khawla said there were 4,000 fighters, mostly Arabs and mostly from Deir al-Zor, in the Deir al-Zor military council which he heads.

They had taken part in all the campaigns the SDF had waged and were now fighting inside Raqqa, he said.

The Syrian army is advancing along the south and west bank of the Euphrates towards where the city of Deir al-Zor is located, while the SDF is mostly on the north and east bank, where Raqqa is located.

This story was edited by Al-Ahram Online