Clearing unexploded Israeli cluster bombs from southern Lebanon could take 12 months, the head of the UN weapons clearance team there has told the BBC.
The unexploded bomblets are the size of a drinks can
Chris Clark, head of the UN Mine Action Service in southern Lebanon, said 22 people have been injured, but none killed, while handling live munitions.
"Bomblets" have already been found at 30 locations, but Mr Clark said he expected a final total of over 100.
Israel says all munitions it uses in conflict comply with international law.
But the New York-based group Human Rights Watch has accused Israel of acting outside the rules of war by firing cluster bombs into civilian areas.
Critics of cluster bombs say the relatively high numbers of unexploded bomblets can kill and maim long after conflict has ended.
All Israeli cluster bombs found in southern Lebanon were contained in artillery shells, the UN said, and were not dropped from planes overhead.
Speaking to the BBC from Tyre, southern Lebanon, Mr Clark said UN mine clearance teams had inspected just 40% of sites known to have been hit by Israeli munitions during the recent conflict with Hezbollah.
"The picture is still emerging at the moment, but there is a general spread of these munitions throughout southern Lebanon," Mr Clark said.
The Mine Action Service had a presence in southern Lebanon long before this year's fighting, clearing mines and unexploded ordnance from previous conflicts.
But Mr Clark said the aftermath of the recent fighting had to take precedence over the search for mines laid during Israel's 18-year occupation of southern Lebanon.
"Now there is a whole new problem here. In terms of the new problem I would like to think that we could get it under control in six months and complete clearance in 12 months."
Thousands of Lebanese have been returning to their homes to inspect damage caused by Israeli air strikes and clashes on the ground between Israeli troops and Hezbollah fighters.
Mine clearing teams in the area, as well as Human Rights Watch, have warned of the dangers of casualties as people clear rubble from homes and roads.
Dense sandbags are used to dispose of unexploded bomblets
Mr Clark hopes further casualties can be minimised by telling people to stay away from the bomblets, which resemble the bulky batteries often used in torches.
The director of Human Rights Watch, Kenneth Roth, has warned that cluster bombs with high failure rates "effectively become anti-personnel landmines", and that their use in civilian areas breaks a legal ban on indiscriminate attacks.
In response, the Israeli military told the BBC: "All the weapons and munitions used by the Israel Defence Forces are legal under international law and their use conforms to international standards."