A 71-year-old Israeli archaeologist has been killed in a Hezbollah ambush in Lebanon after he entered the country with Israeli troops to visit an ancient site.

Zeev Erlich, a renowned historian, had reportedly made an unauthorised visit to the warzone with a senior Israel Defense Forces (IDF) officer on Wednesday.

According to the initial IDF investigation, Col Yoav Yarom, the chief of staff of the Golani Brigade, accompanied Mr Erlich on his trip inside southwest Lebanon to examine an ancient fortress.

Mr Erlich was armed and dressed in IDF uniform despite not being an active duty soldier or in the reserves, Israeli media reported. He was described as a former reservist major.

The archaeological site was thought to have been cleared by the IDF before Mr Erlich, Col Yarom and two other soldiers accompanying them arrived.