Israel has been accused of "shocking" and "completely immoral" behaviour by the UN's humanitarian chief because it dropped cluster bombs on Lebanon when a ceasefire with Hezbollah was in sight.

Jan Egeland told a UN news conference that Israel had either made a "terribly wrong decision" or "started thinking afterwards".

Mr Egeland's unusually harsh remarks came as Lebanon today rejected overtures by Israeli Prime Minister Ehud Olmert to agree to a permanent peace deal with Israel - the first time such a deal would have been agreed since Israel declared statehood in 1948.

Only Jordan and Egypt are formally at peace with Israel, but Lebanon's Prime Minister Fouad Siniora but "will be the last Arab country that could sign a peace agreement with Israel".

In reality, agreeing to any such deal would be a huge risk for Mr Siniora politically because Lebanon is religiously very diverse and many of its denominations are very hostile to Israel. In addition, the Shia Muslim guerilla group Hezbollah has two Cabinet Ministers in the Lebanese Government itself.

Mr Egeland's remarks were arguably the strongest used by UN officials since the war between Hezbollah and Israel - which killed more than 1,000 - came to an end. "What's shocking and I would say, to me, completely immoral, is that 90 per cent of the cluster bomb strikes occurred in the last 72 hours of the conflict, when we knew there would be a resolution," Mr Egeland told the news conference.

A terse Israeli army reply referred reporters to its earlier statement that all the weapons it uses "are legal under international law and their use conforms with international standards."

Cluster bomblets, which have the explosive force to destroy armoured vehicles, are packed into bombs dropped from aircraft or into artillery shells. Between 200 and 600 of the bomblets are typically scattered over an area the size of a football pitch from a single cluster-bomb canister.

An unusual number of cluster bombs used in the war did not detonate on impact, possibly because they were old, Mr Egeland said. Usually 10-15 per cent of the bomblets fail to explode immediately. According to some estimates, up to 70 per cent of the Israeli bomblets failed to explode initially. Civilians returning to their homes in southern Lebanon are experiencing "massive problems," as a result of these unexploded munitions, Mr Egeland said.

"We're finding strikes that are in people's houses, in the middle of the street, around hospitals," said Chris Clark, program manager of the UN Mine Action Co-ordination Center in southern Lebanon. Approximately 250,000 Lebanese of the one million displaced cannot move back into their homes, many because of unexploded munitions.

"Every day people are maimed, wounded and are killed by these ordnance," Mr Egeland declared.

UN and human rights organisations said yesterday that 13 people, including three children, had been killed between the August 14 cease-fire and Tuesday, and 46 people have been wounded.

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