Tests conducted by Lebanese authorities have confirmed that human remains found along the Syrian border belonged to soldiers held hostage by the Islamic State group, an army source said Wednesday.

The troops were kidnapped by IS in 2014, when jihadists overran the Lebanese border town of Arsal, and their families had long lobbied the Beirut government for information on their fate. 

After Lebanon's army waged a week-long assault on IS along the border with Syria last month, it retrieved human remains suspected to belong to the soldiers. 

"The army chief Joseph Aoun met with the soldiers' families today... and informed them of the official DNA results," the army source told AFP.

The source confirmed that the remains belonged to 10 soldiers, including two who were executed separately by the jihadists and the eight that were held by IS.

An army statement confirmed that Aoun had met with a delegation of the soldiers' families. 

The army had said those missing soldiers were its "top concern" in the offensive it fought last month against an estimated 600 IS jihadists entrenched in the border region.

The assault coincided with a simultaneous assault by Shiite militant group Hezbollah from the Syrian side of the frontier.

Fighting ended in a controversial deal between Hezbollah and IS that saw the jihadists evacuated from the border area and into eastern Syria.

Lebanese authorities said that surrendered IS fighters led them to the human remains. 

The soldiers will be buried on Friday, which has been declared a national day of mourning.

An event commemorating the troops will be held outside Beirut and attended by top officials.

The war ravaging neighbouring Syria since 2011 has overflowed into Lebanon, with jihadists claiming several deadly bombings and clashing with the army on multiple occasions.