Smoke billows over southern Lebanon, amid ongoing cross-border hostilities between Hezbollah and Israeli forces, as pictured from Marjayoun, near the border with Israel. (REUTERS/Karamallah Daher)

Israel's military said it hit dozens of Hezbollah targets overnight, a day after carrying out airstrikes against the group which Lebanese authorities said killed nearly 500 people and sent tens of thousands fleeing for safety.

Hezbollah said it targeted several Israeli military targets overnight including an explosives factory and an airfield.

Calls for diplomacy are growing as the conflict worsens, with UN human rights chief Volker Turk urging all states and actors with influence to avert further escalation in Lebanon.

The Kremlin said Israeli strikes on Lebanon could destabilize the Middle East.

The European Union's foreign policy chief said that the escalation between Israel and Hezbollah is almost a full-fledged war and the situation is extremely dangerous and worrying. Josep Borrell told reporters that efforts to reduce tensions were ongoing, but Europe's worst fears about a spillover were becoming a reality.

The foreign ministers of the Group of Seven (G7) warned that actions and counter-actions in the Middle East risked dragging the region into a broader conflict that no country would gain from.