The Israeli army said Sunday one of its drones had come down in Lebanese territory, following a reinforcement of its presence at its northern frontier near Lebanon.

The drone fell "during IDF operational activity" along the border, the army said in a statement.

"There is no risk of breach of information." 

Israel regularly deploys drones over Lebanon, in particular to monitor the movements of pro-Iran armed group Hezbollah, an arch-enemy of the Jewish state and a heavyweight in Lebanese politics.

During a visit on Sunday to a military base near the border, Israeli Defence Minister Benny Gantz said that "Lebanon and Syria are responsible for what happens on and from their territory". 

"We are not trying to escalate the situation, but whoever wants to test us will see a very strong reaction," Gantz warned, according to a statement from his office. 

Israel is technically at war with neighbouring Lebanon and Syria, and has carried out hundreds of strikes on Syrian soil to prevent Iran, which backs Hezbollah and the Damascus regime, from gaining a foothold there.

Israel this week reinforced its troop presence on its northern border in what several Israeli media outlets said was a response to an increased threat from Hezbollah.

On Monday, five Iran-backed fighters were killed in an Israeli missile strike south of the Syrian capital Damascus, according to the Syrian Observatory for Human Rights. 

Hezbollah said one of its fighters was also among the dead.

Israel announced initial reinforcements to the north on Thursday and additional measures on Friday.

Hours later it struck military targets in southern Syria in retaliation for earlier "munitions" fire towards Israel from inside Syria. 

The army said that in ordering the redeployment it had "elevated its readiness against various potential enemy actions".