Israeli warplanes hit a UN observation post during a raid in south Lebanon Tuesday, Lebanese police said.

The post was hit in the hilltop town of Khiam, which sheltered an infamous prison during Israel's 22 year occupation of south Lebanon to 2000 but is now a Hezbollah stronghold, the police said.

There was no immediate word on the condition of the UN peacekeepers inside the post.

The UN Interim Forces in Lebanon (UNIFIL) were not immediately reachable for comment.

An AFP correspondent across the border in the town of Metulla in the far north of Israel saw a heavy bombardment under way of the Khiam area.