The top U.N. humanitarian aid official has condemned Israel's use of cluster bombs in the final days of its offensive in Lebanon. It may take years to clear the unexploded bombs.

Jan Egeland (file photo)

Humanitarian aid chief Jan Egeland said U.N. mine experts have identified more than 350 cluster bomb strike locations in Lebanon. He says the sites are contaminated with more than 100,000 unexploded bomblets.

As he prepared to leave for a Lebanon aid conference in Stockholm, Egeland said Israeli forces had dropped many of the bombs in the final hours of their recent offensive in southern Lebanon.

"What is shocking and I would say completely immoral is that 90 percent of cluster bomb strikes occurred in the last 72 hours of conflict, when we knew there would be a resolution, when we knew there would be an end of this," said Jan Egeland.

Lebanese child injured by an Israeli cluster bomb

Egeland called it "an outrage" that there are now 100,000 unexploded bombs in civilian areas.

"Either a terribly wrong decision was made, or one did something that was very wrong, one bombed first and then one started thinking afterwards," he said. "Civilians will die disproportionately again, not only during the war, but after the war as well. [This] should not have happened."

Egeland said it would take up to two years to clear the contaminated areas. He called on the United States, which manufactured some of the bombs, to talk with Israeli officials about the dangers posed to non-combatants.

Israel earlier said all of the munitions used during its Lebanon operations were in compliance with international laws.

Egeland, however, called the use of cluster bombs a "disproportionate response" to the Hezbollah rockets fired into Israel.

"I said very clearly that the response was excessive and disproportionate as I also clearly blamed, we clearly blamed, from Hezbollah strongholds, Hezbollah blending into the civilian population and sending their rain of rockets from civilian areas, then in a way inviting this response," noted Jan Egeland.

Egeland said 75 percent of the one million people displaced by the conflict in southern Lebanon have returned. But he said one-third of the returnees were unable to move into their homes, either because the buildings had been destroyed or because of the danger of unexploded bombs.

He said the U.N. will not be increasing the amount of its own humanitarian appeal for Lebanon, but will support the Lebanese government's appeal at the Stockholm conference. More than 60 nations are expected to attend the Stockholm meeting in hopes of raising $500 million for the recovery effort.

A separate conference will be held in Stockholm later in the week to raise funds for humanitarian efforts in the occupied Palestinian territories.