A member of the United Nations peacekeeping force in southern Lebanon (UNIFIL) was killed on Wednesday, a U.N. spokesman said, without giving details of how.
The incident happened in Ghajar, Tenenti said, a village which straddles the Israel-Lebanon frontier. Israel and Hezbollah have been trading fire on Wednesday around the frontier area.
"One peacekeeper was killed. We are looking into the circumstances of this tragic incident," said Andrea Tenenti, spokesman for the United Nations Interim Force in Lebanon.
Spain's Prime Minister Rajoy Brey confirmed the death of a Spanish soldier in Lebanon and said in a Twitter message that he sent his condolences to the soldier's family.
Tenenti said the head of UNIFIL was in close contact with all parties and had urged "maximum restraint" to prevent an escalation.
UNIFIL has more than 10,000 troops in Lebanon after its expansion under the U.N. Security Council resolution that halted the 2006 Israel-Hezbollah war in southern Lebanon.
It operates alongside Lebanese troops who are deployed in the south to keep peace near the frontier with Israel and prevent weapon transfers in an area that is a stronghold of Hezbollah.