Dubai: Lebanon will show “no leniency” in its fight with terrorists on the Syrian border as troops battled the Al Qaida affiliated group, Al Nusra Front, for a third day on Monday in violence that threatens to worsen sectarian tensions in the country and test the unity of the armed forces.

Sixteen Lebanese soldiers, including two officers, and “dozens” of militants have been killed and 22 soldiers missing following the clashes with Islamist militants, according to the army.

Soldiers fired mortar shells at militant positions in the mountains around the border town of Arsal, in eastern Lebanon, and the sound of heavy machinegun fire could be heard, witnesses said. Thick black smoke rose on Monday from a petrol station set alight during the fighting as thousands of civilians and Syrian refugees crammed into cars and pickup trucks and fled the town.

Speaking after a cabinet meeting, Prime Minister Tammam Salam also urged France to speed up a pledged delivery of weapons to the army.

“We stress that there will be no leniency towards the terrorist killers and no appeasement for those who violate Lebanon’s territory and harm its people,” the premier said.

“There can be no political solutions with takfiris (extremists),” he added.

“The only solution is the withdrawal of the gunmen from Arsal and its surroundings and the return of the state and all its agencies to this area that is dear to the Lebanese.”

It was was the most serious spillover into Lebanon of the three-year conflict in Syria, which has also ignited clashes between supporters and opponents of Syrian President Bashar Al Assad in Lebanon and sparked Beirut terror bombings.

On Monday, the Syrian foreign ministry issued a statement expressing its “support and solidarity with the Lebanese army as it faces terrorist groups.”

The violence in the eastern Lebanese region began on Saturday afternoon, after soldiers detained a Syrian man, Emad Ahmad Jumaa, who the army said confessed belonging to Al Nusra Front.