DAMASCUS, Dec. 29 (Xinhua) -- U.S. helicopters have transferred commanders of the Islamic State (IS) group from the eastern province of Deir al-Zour to areas in the northeastern province of Hasakah, state news agency SANA said Friday.

U.S. helicopters coming from the northern countryside of Deir al-Zour landed near the al-Basel Dam south of Hasakah, transporting leaders of the IS who surrendered to the U.S.-backed Syrian Democratic Forces (SDF), said SANA.

It's not the first transfer of IS leaders, said SANA, adding that earlier this month U.S. helicopters transferred 47 IS leaders to the same area in Hasakah, many of whom had fled the areas due to the military operations of the Syrian army.

SANA said the injured IS leaders were medically treated by the Doctors Without Border organization.

The report renewed accusation that Washington is supporting IS in eastern Syria.

The SDF, an alliance of Kurds, Arabs, and Assyrians, has controlled areas in the northern countryside of Deir al-Zour with the backing of the U.S., following their capture of the northern city of Raqqa, the de facto capital of IS.

The Syrian government refused to acknowledge the liberation of Raqqa, saying it's still occupied by the U.S. and the Kurdish-led fighters.

In his recent comments, Deputy Foreign Minister Faisal Mekdad said the SDF was "the new Daesh," using the Arabic acronym of IS.

He said the SDF should either return under the umbrella of the Syrian Arab Republic, or they would meet similar destiny of IS.

His remarks reflected the dismay of the government with what is perceived to be a separatist move by the Kurdish-led groups in northern Syria.

With the tension brewing between the Kurds and the Syrian government, despite the fact that both had a role in defeating IS, recent reports suggested that the U.S. is about to throw a heavy support behind the SDF in weapons and military gears.