SYRIAN and Iraqi forces surrounded and attacked the last major Isis stronghold of Abu Kamal yesterday in a cross-border offensive.

Syrian government troops, allied militia fighters and the Iraqi Popular Mobilisation Units (PMU) were battling their way into the town on the south-eastern border.

Hezbollah sources said the joint force advanced from al-Qaim to the south, just across the border in Iraq.

Iraqi forces took al-Qaim late last week, leaving only the small town of Rawa occupied by the death cult.

Anonymous Iraqi spooks claimed that Isis leader Abu Bakr al-Baghdadi had fled from Rawa to Abu Kamal by taxi.

Earlier, Syrian soldiers and Hezbollah guerillas advancing from the T2 air base joined Iraqi troops on the border west of Abu Kamal and al-Qaim. Video footage showed the Hezbollah flag flying on the frontier.

Isis still controls the Akash oil fields to the north of the border.

On Tuesday, the Syrian army began a separate push towards Abu Kamal from the north-west down the west bank of the River Euphrates from the recently captured town of al-Mayadeen.

Russian news agency RIA Novosti claimed that locals had seen US helicopters evacuating Isis commanders before the army retook the town last month.

Army veteran turned shepherd Muhammad Awad Hussein, who said he had been trained to identify US aircraft, said US jets had launched an air strike near a farm as cover for the operation.

“We tried to hide and saw several US helicopters,” he said. “There were foreign Isis commanders on the ground, who were waiting for them next to their headquarters … The helicopters took them out of Mayadeen.”

Syrian troops captured a huge Isis arms cache after entering al-Mayadeen, including US, British and Belgian-made weapons.