A general view of a base of the United Nations peacekeeping forces in Lebanon (UNIFIL) at the Lebanese-Israeli border, in the southern village of Markaba. File/AP

United Nations peacekeepers said three military observers and a translator were wounded Saturday in a blast in southern Lebanon, where Israel and Hezbollah trade frequent cross-border fire.

The military observers, from Australia, Chile and Norway, and a Lebanese language assistant had been on foot patrol around the so-called Blue Line — the UN-demarcated border between Israel and Lebanon.

The four "were injured when an explosion occurred near their location", according to Andrea Tenenti, a spokesperson for the United Nations Interim Force in Lebanon.

The personnel were working for the UN Truce Supervision Organization, which supports the UN peacekeeping force.

They were "evacuated for medical treatment" and were in a stable condition, Tenenti said, adding the United Nations was "investigating the origin of the explosion".

Flags fly at half-staff, at the UNIFIL headquarters in the southern Lebanese town of Naqoura. File/AP

Israel and Lebanon's Iran-backed Hezbollah have exchanged near-daily fire since Palestinian group Hamas carried out an unprecedented attack on southern Israel on October 7, triggering war in Gaza.

Lebanon's state-run National News Agency reported an "enemy (Israeli) drone" raided the Rmeish area of southern Lebanon where the incident is said to have occurred.

Lebanese Prime Minister Najib Mikati condemned what he called a "dangerous incident", while his foreign ministry said the attack was "in violation of international law".

The Israeli army told AFP in a statement: "We did not strike in the area."

Hezbollah, which has a powerful arsenal of rockets and missiles, says its attacks on Israel are in support of Hamas.

Agence France-Presse