By Angus McDowall

BEIRUT (Reuters) – A convoy of Islamic State fighters and their families began to depart the Lebanon-Syria border zone on Monday under Syrian military escort, surrendering their enclave and leaving for eastern Syria after a week-long battle.

A line of ambulances and buses were shown on Syrian state television driving slowly through the arid countryside, the border’s pale hills behind them, as they departed.

It will end any Sunni militant presence on the border, an important goal for Lebanon and the Shi’ite Hezbollah group, and is the first time Islamic State has publicly agreed to a forced evacuation from territory it held in Syria.

Islamic State agreed a ceasefire on Sunday with the Lebanese army on one front and the Syrian army and Hezbollah on the other after losing much of its mountainous enclave straddling the border, paving the way for its evacuation.

Both Hezbollah and Lebanese officials have billed the evacuation as a surrender by the jihadist group.

“We do not bargain. We are in the position of the victor and are imposing conditions,” Lebanese Internal Security General Abbas Ibrahim said on Sunday.

Hezbollah, a Lebanese group, has been a close ally of Syrian President Bashar al-Assad through Syria’s six-year civil war. The Lebanese army said its offensive against Islamic State did not involve coordination with Hezbollah or the Syrian army.

A commander in the pro-Assad military alliance said Syria and Hezbollah had accepted Islamic State’s evacuation rather than a fight to the end to avert a bloody war of attrition.

Islamic State fighters were sheltering among civilians and to complete the offensive would have involved great bloodshed, the commander added. “Every battle that ends with negotiation or surrender is a victory,” the commander said.

HEAVY SECURITY

A total of 600 people, including both Islamic State fighters and their family members, will leave in the convoy, Syria’s state-run Ikhbariya television station reported.

The militants will travel across Syria under heavy security escort to Islamic State lines near Al-Bukamal in the east, a Lebanese security source said.

The Syrian army and Hezbollah were communicating with Islamic State near Al-Bukamal to arrange the transfer of the convoy into jihadist territory, the security source said.

One Hezbollah prisoner and the corpses of five Hezbollah fighters, as well as the bodies of some Syrian soldiers, will be handed over by Islamic State, the security source added.

Islamic State fighters were earlier seen burning heavy equipment and arms which the left in the border enclave.

The deal also involved Islamic State revealing the fate of nine Lebanese soldiers it captured when it overran the town of Arsal in Lebanon in 2014.

A senior Lebanese security official said late on Sunday the soldiers were almost certainly dead after recovering six bodies and digging for two others in areas previously held by Islamic State.

Earlier this month, two other pockets straddling the border were recaptured by Lebanon and Syria after other militant groups accepted similar evacuation deals.

Those agreements were prompted by a brief Hezbollah offensive that began at the end of July against militants of the group formerly known as Nusra Front, which was al Qaeda’s official partner in Syria until last year.

Hezbollah has maintained a strong presence in the parts of Syria near the border with Lebanon for years, helping Assad to recapture several rebel-held towns and villages there.

The threat to Lebanese territory from rebel and militant groups in Syria was evident in the 2014 attack on Arsal. Suicide bomb attacks struck a predominately Shi’ite area in south Beirut, where Hezbollah is widely supported, in November 2015.

Inside Syria, Islamic State is retreating on all fronts, losing territory both to the Syrian army and its allies, and to an alliance of Kurdish and Arab militias backed by a U.S.-led coalition.

(Additional reporting by Sarah Dadouch; Editing by Richard Balmforth and Alison Williams)