US forces to complete withdrawal from Syria within a month: sources

US forces that led the anti-Islamic State coalition in Syria will complete their withdrawal from the country within a month, three sources told AFP on Monday.

"Within a month, they will have withdrawn from Syria and there will no longer be any military presence in the bases," a Syrian government official said, with a Kurdish source confirming the development. A third source, a diplomat, said the withdrawal should be completed within 20 days.

The United States began withdrawing on Monday from Qasrak, a major base in a northeastern region still under the control of Kurdish forces.

An AFP team saw a convoy of dozens of trucks, loaded with armoured vehicles and prefabricated structures, on a road linking the Qasrak base in Hasakeh province to the border with Iraq.

The US forces are reportedly headed towards Iraqi Kurdistan. 

The move comes after Kurdish forces, long backed by Washington in the fight against the Islamic State group, ceded territory to Damascus and agreed to integrate into the state.

American forces have already withdrawn from two other bases in the past two weeks, Al-Tanf in the southeast and Shadadi in the northeast.

Syria's government recently extended its control to the northeast of the country.

With this withdrawal, the international coalition now has only one base remaining in Syria: the Kharab al-Jir base near the town of Rmeilan, south of Hasakah. The United States has about 1,000 troops still deployed in Syria.