"We have requested with the relevant parties that the cases be investigated and prosecuted by national authorities to bring the perpetrators to justice and ensure criminal accountability for crimes against peacekeepers," Stephane Dujarric, spokesman for the UN secretary-general, told reporters.

On March 29, an Indonesian peacekeeper was killed and three others wounded by a projectile that exploded near a UN Interim Force in Lebanon (UNIFIL) position.

The next day, two other soldiers from the same force were killed by an explosion that destroyed their vehicle. A third was seriously wounded and a fourth more lightly.

In the first case, the investigation indicates "the projectile was a 120 mm tank main armament round, fired by an Israel Defense Forces Merkava tank from the east," Dujarric said.

He added that UNIFIL had communicated the location of all its positions and installations to the Israeli military twice in the days before the incident.

The March 30 explosion was caused by an IED, Dujarric said.

"The investigation has assessed that, given the location of the incident, the nature of the explosion, and the current context, the IED was most likely placed by Hezbollah," he said.

UNIFIL has served as a peacekeeping force between Israel and Lebanon since 1978 but now finds itself caught in the crossfire between the Israeli army and Iran-backed Hezbollah.