United Nations peacekeepers said three military observers and a translator were wounded Saturday in a blast in southern Lebanon, where Israel and Hezbollah militants 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”.