US 'evacuates base' in Syria's southern desert

US military forces and allied Arab fighters have evacuated a base set up in June in the Syrian desert near the Iraqi border and have relocated to the larger Tanf base, rebel sources said on Tuesday.

The Zakf base was created to halt the advances of Syrian regime forces and Iranian-backed militias from territory near Tanf after they encircled rebels backed by Washington.

The decision to evacuate the base comes following a deal between Washington and Moscow.

"We have left the garrison after our allies reached an agreement with Russia to pull back to Tanf," a source who belongs to the Pentagon-backed Maghawir al-Thawra rebel group, told Reuters.

"We have moved all the equipment and destroyed some of the fortifications so they are no longer usable," the source added.

Western-backed rebels had aimed to use the base to recapture more territory along the Iraqi border and push towards Deir az-Zour in eastern Syria.

Recent advances by the Syrian regime and its allies towards the city would make any rebel advance from the south redundant.

"The base was a first line of defence and now the justification behind it is no longer present and the aim is to concentrate in Tanf," a senior commander in the Maghawir al-Thawra group said.

The latest agreement between the US and Russia comes as part of wider efforts to broker a ceasefire in the south of the country.

"This is the latest outcome of the ongoing secret US-Russian talks over southern Syria," a Western diplomat told Reuters.

Russian and US officials met secretly in Jordan in June and announced a ceasefire agreement in Syria's southwest a month later.

The truce has reduced fighting in the area and is meant to lead to a permanent de-escalation.

Most Iranian-backed forces have left the area around Tanf as fighting has moved to Deir az-Zour, the diplomat added.

Western and Arab countries have been pressuring the rebel groups which they back to leave the desert area and retreat to Jordan, a request the groups have so far ignored.

Tanf is the only location with a significant US military presence in Syria outside of Kurdish-controlled areas in the north.