"Captain Eitan Itzhak Oster, aged 22... fell during combat in Lebanon," the military said in a statement.

A military website said Oster was killed on Wednesday, without providing further details.

Hezbollah said its fighters were clashing with Israeli troops who had "infiltrated" a southern border village.

The group said earlier it had forced Israeli soldiers to withdraw after they attempted to enter the border village of Adaysseh further northeast.

It was the first time the Iran-backed group said there was fighting on Lebanese soil since the start of an escalation in recent weeks when the Israeli army began pounding south Lebanon and later killed Hezbollah leader Hassan Nasrallah in an air strike.

"This is just the start of the confrontation," Hezbollah spokesman Mohammad Afif told media on a tour in the Lebanese capital's southern suburbs.

"The resistance in the south is at its highest level of readiness," he added, referring to Hezbollah fighters.

The Lebanese army also said Israeli forces had briefly breached the demarcation line between the countries.

"Israeli enemy forces breached the Blue Line by approximately 400 metres (yards) into Lebanese territory" in two areas, "then withdrew a short time later", it said on X.

Earlier Wednesday, the Israeli army called for the evacuation of additional areas in southern Lebanon, telling residents to leave over 20 villages and towns in south Lebanon.

The move came a day after a similar evacuation call was made by the Israeli military as it announced the launch of ground operations.