ISIS pushed back US proxy forces from a Syrian town on the border with Iraq yesterday.

The US-allied New Syrian Army (NSA) had captured the Hamdan air base near the town of Boukamal overnight but were driven back by the Islamist militants yesterday.

NSA spokesman Mozahem al-Saloum said his men were airlifted into the area on US-led coalition helicopters.

The army’s rapid advance has left it in nominal control of most of the barren southern border with Jordan and Iraq in Rif Damashq, Homs and Deir Ezzor provinces.

Earlier this month it emerged that British SAS troops had entered Syria from western Iraq to help the NSA — without the approval of Damascus or Westminster.

Boukamal lies on the Euphrates river across the border from the Iraqi town of Qa’im.

The ultimate aim of the NSA offensive may be to seize control of the government-held city of Deir Ezzor, currently besieged by Isis, and the surrounding oilfields with the aim of partitioning Syria along sectarian lines.

Other Western-backed factions allied to al-Qaida’s Syrian branch the Nusra Front continued their repeated breaches of the Russia-US-brokered ceasefire on Tuesday.

And two dozen Syrian opposition groups threatened to boycott peace talks unless the UN imposed a “no-bombing zone for all of Syria” and dropped aid to terrorist-held areas “irrespective of Syrian regime consent.”