A Lebanese soldier was killed Friday as a military bus came under fire in the country's north, in the fourth such deadly attack in less than a month, the army said.

It named the soldier as Jamal Jean Hashem, a teenager on the bus which was transporting soldiers back to their post in the Akkar region of northern Lebanon.

On September 23, gunmen shot dead a soldier in the nearby port city of Tripoli, the frequent scene of clashes between the army and Sunni extremists.

And a homemade bomb exploded in the city on October 7 killing another soldier, while a colleague died in an attack in the Akkar region two days later by gunmen on a motorbike.

"Terrorist groups are targeting the army to weaken it and ... to force the army to ease the pressure in the Arsal region" of east Lebanon on the border with Syria, a military source told AFP.

Jihadists from the Islamic State group and Al-Qaeda's Syrian affiliate Al-Nusra Front fought deadly battles with Lebanese troops in Arsal in August.

They withdrew after a truce to mountains outside the border town, but took dozens of army and police hostages with them as they left. Three of them have since been executed.

The Sunni extremists demand the withdrawal from Syria of fighters from Hezbollah and they accuse the army of cooperating with the powerful Lebanese Shia militant group.