Four UN observers were killed Tuesday when an Israeli aerial bomb struck their base in southern Lebanon.  There are unconfirmed reports a Canadian is among the dead.

A bomb directly hit the building of the observer force in the town of Khiam near the eastern end of the border with Israel, said Milos Struger, spokesman for the UN peacekeeping force in Lebanon known as UNIFIL.

Struger said UNIFIL had dispatched a rescue team which was trying to clear the rubble when it came under more fire from Israeli forces.

A senior Lebanese military official said the dead included observers from Canada, Austria, China and Finland. 

However, the Department of National Defence has not confirmed the report. The federal government would only say there's been a significant incident involving a Canadian UN observer.

One Canadian soldier, with the Princess Patricia's Canadian Light Infantry,  is currently serving with the UN at the base in Khiyam as part of  a mission called Operation Jade.

Annan reacts strongly

"I am shocked and deeply distressed by the apparently deliberate targeting by Israeli Defence Forces of a UN Observer post in southern Lebanon that has killed two UN military observers, with two more feared dead," said UN Secretary-General Kofi Annan, after rushing out of a meeting with U.S. Secretary of State Condoleezza Rice and Lebanese Prime Minister Fuad Saniora.
 
"This coordinated artillery and aerial attack on a long established and clearly marked UN post at Khiyam occurred despite personal assurances given to me by Prime Minister Ehud Olmert that UN positions would be spared Israeli fire."

But, Israel's ambassador to the UN denied his country would deliberately target a UN post.

"I am shocked and deeply distressed by the hasty statement of the secretary-general, insinuating that Israel has deliberately targeted the U.N. post," said Dan Gillerman.

Gillerman said Israel would investigate: "We do not have yet information what caused this death: it could be the IDF (Israel's military), it could be Hezbollah."

Charles Kupchan, a senior fellow with the Council on Foreign Relations, said he was surprised by Annan's comments.

"Israelis have generally gone out of their way to avoid civilian targets," he told CTV Newsnet.  "So why Annan would come out with a statement like that is, I think, quite surprising."

Kupchan said it was too early to speculate on how or why the post was bombed, but said that in some cases UN and Hezbollah camps are right next door to each other.

But, Sunil Ram, a defence and security analyst, told CTV Newsnet that the Israelis had shelled the base at least 14 times before bombing it with what was clearly a guided bomb.

"UN posts like this are very well marked. The Israelis knew it was there; it's been there for years.

"But then when the Indians tried to send a rescue mission in there, they then shelled the troops who were trying to get to the post. So how much more deliberate do you want it to be?"

On Monday, vans marked with Red Crosses had come under fire.

Beirut struck again

Tuesday's bombing came as Israeli forces pushed deeper into southern Lebanon, part of a campaign to stop Hezbollah missiles.

Israel also pounded Beirut with new air strikes, marking the first attacks in Lebanon's capital in almost two days.

At least four large blasts were heard as a heavy gray cloud was seen billowing from the southern district -- a Hezbollah stronghold that has been heavily bombarded.

Al-Jazeera TV reported 20 Israeli rockets hit the Dahiyah neighborhood as a succession of blasts set off car alarms in central Beirut and sirens were heard.

In return, Hezbollah rained rockets down on the northern Israeli city of Haifa, injuring at least five people.

Hezbollah's leader, Sheik Hassan Nasrallah, issued a taped television message saying guerrillas would now start firing rockets deeper into Israel, beyond the northern port city of Haifa.

with files from Associated Press