German Chancellor Olaf Scholz on Monday expressed "great concern" about the "spiral of violence" in the Middle East in a phone call with Iranian President Masoud Pezeshkian, his spokesman Wolfgang Buechner said in a statement.

Scholz "appealed to President Pezeshkian to do everything possible to prevent a further military escalation", expressed "great concern about the danger of a regional conflagration in the Middle East" and said "the spiral of violence in the Middle East must be broken now".

Five Iran-backed fighters have been killed in a drone strike in Syria's east, near the Iraqi border, a war monitor said, adding it was not clear yet who was behind the attack.

"Five pro-Iranian fighters were killed and others were injured, some severely... after an unknown drone targeted the military vehicle they were in... near the Syrian-Iraqi border," said the Syrian Observatory for Human Rights.

Air France and its subsidiary Transavia France have again extended the suspension of their flights to Beirut, through Wednesday August 15, because of continued tensions in the region, the companies said on Monday.

The flights have been suspended since July 29 because of the "security situation in Lebanon" and their resumption "will be subject to a new assessment of the situation on the ground", Air France said in a statement.

Hezbollah launched overnight into Monday salvos of rockets "in response" to Israeli attacks on south Lebanon, targeting troops stationed in northern Israel.

"Approximately 30 projectiles were identified crossing from Lebanon toward the area of Kabri," the Israeli military said Monday, reporting no casualties and announcing retaliatory strikes.

Hezbollah said it launched on Saturday explosive-laden drones at a north Israel army base following the killing of a Hamas commander in south Lebanon a day earlier.

Hezbollah fighters launched "squadrons of explosive-laden drones" at the Michve Alon base near the Galilee town of Safad "in response to the attack and assassination carried out by the Israeli enemy in the city of Sidon" on Friday, the group said in a statement.

Iraq's top Shiite Muslim cleric Grand Ayatollah Ali Sistani has warned of the risk of a regional escalation with potentially "catastrophic consequences" following the killing of two Iran-backed militant leaders.

Sistani also urged an end to the "genocidal war" in Gaza, where the civil defense agency said an Israeli air strike Saturday on a school housing displaced Palestinians killed more than 90 people.

Thousands of Ukrainian troops are taking part in an incursion aiming to destabilize Russia by showing up its weaknesses, a top Ukrainian official has told AFP as the assault entered its sixth day.

Fears of a major escalation between Israel and Hezbollah have left many Lebanese on edge, exacerbating mental health problems and reviving traumas of past conflicts in the war-weary country.

One 29-year-old woman, who lives near the southern city of Sidon, said she dreaded the thunderous, explosive boom of Israeli jets regularly breaking the sound barrier.

Haifa's residents gaze warily on to the sprawling industrial port that flanks their Israeli city, knowing the potential for a major blast as they brace for possible bombardment from Hezbollah.

The historic city cascades down a steep hillside to the very edge of the port, a complex which contains Israel's biggest oil refinery, giant fuel tanks and other highly flammable targets.

Moscow on Saturday mounted an operation in three border regions adjoining Ukraine to halt Kyiv's biggest cross-border offensive in the two-and-a-half-year conflict.

Ukrainian units stormed across the border into Russia's western Kursk region on Tuesday morning in a shock attack and have advanced several kilometers, according to independent analysts.