Hezbollah militants targeted Israeli soldiers near the Lebanese border village of Labbouneh with artillery shells and rockets on Wednesday, the group said, a day after Israel said it had killed two successors to Hezbollah's slain leader.

The Iran-backed group, which has been launching rockets against Israel for a year in parallel with the Gaza war and is now fighting it in ground clashes, said it had pushed the troops back.

The escalation in Lebanon and the ongoing one-year-old war between Israel and Hamas in Gaza has raised fears of a wider Middle East conflict that could suck in Iran and Israel's superpower ally, the United States.

The Israeli military said three of its troops were severely injured on Tuesday and Wednesday during combat in southern Lebanon. Sirens sounded in northern Israel on Wednesday morning after Israel renewed bombing of Beirut's southern suburbs, a Hezbollah stronghold, overnight.

The conflict in Lebanon has escalated dramatically in recent weeks as Israel carried out a string of assassinations of top Hezbollah leaders and launched ground operations into southern Lebanon that expanded further this week.

An Israeli military spokesperson declined to say how many troops were in Lebanon, but the military has announced that four divisions are operating on the border, meaning that thousands of soldiers have been deployed.

Overnight, Israel again bombed Beirut's southern suburbs and said it had killed a figure responsible for budgeting and logistics, Suhail Hussein Husseini.

The suburbs, once a densely populated and thriving district, have been emptied of many of its residents by Israeli evacuation warnings. Many Lebanese draw parallels between the warnings and those seen in Gaza over the last year, prompting fears that Beirut could face the same scale of destruction.