"We emphasise that the (Israeli army) is operating precisely against the Hezbollah terrorist organisation and is not operating against the Lebanon Armed Forces," the military told AFP in a statement.

The Lebanese army said Israeli fire killed a soldier Wednesday, a day after it said three other personnel died in a strike on their position in the town of Sarafand, some 40 kilometres (25 miles) from the southern border.

South Lebanon has seen intense fighting between Israel and Hezbollah militants whose group holds sway in the area.

Israel's military said it struck "a terrorist infrastructure site in which a number of Hezbollah terrorists were operating in the area of Sarafand" on Tuesday night.

"The (army) is looking into reports regarding soldiers of the Lebanon Armed Forces who were injured during the strike," it added, but did not refer to the other deadly incident mentioned by the Lebanese army.

Since September 23, Israel has ramped up its bombing campaign in Lebanon, later sending in ground troops, after almost a year of cross-border exchanges begun by Hezbollah in support of its Palestinian ally Hamas.