A ceasefire was reached on Thursday morning near the Lebanese border town of Arsal, where Hizbollah has been fighting extremist militants since last week.
The ceasefire took effect at 6am local time after head of Lebanon’s Directorate of General Security Maj Gen Abbas Ibrahim mediated an agreement between the Shiite group and militants of Jabhat Al Nusra, a former Al Qaeda affiliate, reported Lebanon’s National News Agency (NNA).
The report said that Gen Ibrahim is scheduled to announce the terms of the agreement "at a later time", adding that Al Nusra militants and their families will be heading to Syria’s Idlib in the north-western part of the country – which is largely under control of the extremists.
Hizbollah leader Hassan Nasrallah said in a televised speech on Wednesday evening that the group was close to defeating Al Nusra.
"We are in the face of a very big military victory," he said, adding that the Sunni militants have "effectively lost" most of the land they held in the barren, mountainous border region of Jurud Arsal.
Mr Nasrallah said that Hizbollah would be willing to hand over territory it has captured if the Lebanese army requested it.
The Lebanese Armed Forces did not participate in the offensive but established defensive positions around Arsal, which the Hizbollah chief said were essential.
Hizbollah's militia in Lebanon is considered stronger than the country's military.
Iran-backed Hizbollah, with the Syrian army, had made rapid advances to drive the militants from their last foothold along the frontier.
Mr Nasrallah said that Saraya Ahl Al Sham — a Free Syrian Army rebel faction that was present in the area – pulled its militants from the front lines early in the offensive.
"We facilitated this," he said. "We are ready to work with the Lebanese state and the Syrian government on the withdrawal" of the rebel faction to Syria.
The next phase is expected to target a nearby enclave under ISIL's control.
Hizbollah has been fighting alongside Syrian president Bashar Al Assad's forces since the war broke out in 2011.
ISIL and Al Nusra — who are at war in Syria — have been responsible for a number of deadly bombings in Lebanon since 2013.
Nearly 1.5 million Syrian refugees are in Lebanon, around a quarter of its population, where most live in severe poverty. Tens of thousands of refugees, most of whom live in makeshift camps, live in Arsal.
The Lebanese army says it regularly stages operations targeting ISIL and former Al Qaeda-linked militants in the hills near the border.
In June, the military arrested nearly 400 people when they raided refugee camps in the area after a string of suicide attacks. Four died in army custody.
The army said that the men died from “pre-existing condition”, but, according to Human Rights Watch report, there was evidence of torture on the bodies.