Lebanese army commandos stand on a hill captured from the Islamic State group in Jurud Ras Baalbek along the border with Syria on August 28, 2017 (AFP Photo/PATRICK BAZ)

Lebanese soldiers drive a buggy bearing the Lebanese flag in an area they recently took from the Islamic State (IS) group in Jurud Ras Baalbek on the Syrian-Lebanese border, on August 28, 2017 (AFP Photo/PATRICK BAZ)

Lebanese soldiers stand on armoured vehicles on a hill they took from the Islamic State (IS) group in Jurud Ras Baalbek on the Syrian-Lebanese border, on August 28, 2017 (AFP Photo/PATRICK BAZ)

Jurud Ras Baalbek (Lebanon) (AFP) - The dust-covered soldiers, armoured vehicles and tents may not look very official, but they mark the first time Lebanese troops have deployed in this sliver of land along the Syrian border.

After a week-long campaign against the Islamic State group, Lebanese troops have established an unprecedented presence in the northeastern area of Jurud Ras Baalbek, a belt of territory that has been a longstanding source of contention with Syria.

An evacuation deal led to the jihadists' withdrawal into eastern Syria on Monday, as the Lebanese army organised a press tour of the area.

Dozens of Lebanese troops are manning newly erected outposts on a string of barren hilltops near Syrian territory.

"Before Daesh was here, there was no Lebanese army presence," a member of the special forces' airborne division told AFP, using the Arabic acronym for IS.

"When we advanced, we pulled out the Daesh flag and stuck in a Lebanese flag for the first time," the soldier said, speaking on condition of anonymity.

Lebanon and Syria share a 330 kilometre (205 mile) border, with no official demarcation at several points, including in the northeast.

For years, the mountainous territory now held by the army was expertly navigated by smugglers bringing state-subsidised diesel from Syria into Lebanon.

Syrian troops had also maintained a presence on Lebanese land there, according to Beirut-based geographer Issam Khalifeh, sometimes preventing farmers in the area from tending to their crops.

- 'Closest' to real border -

Damascus and Beirut signed an agreement in 2008 to more clearly demarcate the border, but progress has been slow and the northeastern frontier remained largely uncontrolled -- until now.

"This is the closest that the Lebanese army and state have gotten to completely controlling the border with Syria," said Aram Nerguizian of the US-based Center for Strategic and International Studies.

He said many of the new army positions lay inside territory historically contested by the two countries, closer to where Lebanon says the real border lies.

Many of the soldiers who spoke to AFP on Monday described it as the closest they had ever been to this sector of the border.

"These roads weren't here before. We opened them so that our vehicles could come through," said the special forces member, gesturing to white gravel roads criss-crossing the hilly terrain.

"This is the first time the Lebanese army has an established presence in this area," one heavyset fighter from the 6th Brigades told AFP.

The positions did not appear reinforced yet.

Most soldiers relaxed near armoured cars or in the shade of tents, but some manned vehicle-mounted heavy machineguns pointed at arid valleys below.

After Syria's conflict erupted in 2011, the northeastern border areas were regularly hit by stray shells.

- Battle over 'narrative' -

In 2014, jihadist militants overran both sides of the frontier, including Jurud Ras Baalbek and the Lebanese border town of Arsal further south.

The army launched its operation against jihadists in the area on August 19, coinciding with a simultaneous assault waged from the Syrian side by Lebanese militant movement Hezbollah and the Syrian army.

Lebanese troops had cornered IS into 20 square kilometres of territory (seven square miles) in the border region when a ceasefire deal was announced on Sunday morning.

The agreement was reportedly negotiated between Hezbollah and IS and has seen hundreds of fighters leave the border area for eastern Syria.

Lebanon's army has insisted that there was no coordination with Hezbollah on the offensive.

Hezbollah, which has intervened in Syria's conflict on behalf of the Damascus regime, is the only faction that did not hand over its weapons after the 1975-1990 Lebanese civil war.

Its arsenal is a highly controversial issue in Lebanon.

Late Monday, the group's head Hassan Nasrallah said IS's withdrawal was a "great achievement," calling for celebrations later in the week.

Nerguizian said the Shiite movement was "trying to take credit retroactively" for the success of the Lebanese Armed Forces, which is seen in the country as a rare symbol of national unity, though its military force is rivalled by the powerful Hezbollah.

"The LAF's swiftly executed and successful campaign is not something many Lebanese let alone Hezbollah expected," he told AFP.

With a reinforced troop presence along the border, "the LAF's own national security credentials could challenge Hezbollah's," Nerguizian said.

"In short, the battle against IS in Lebanon may be over, but the war over Lebanon's national security narrative has only just begun."