Air- or ground-launched, the bombs often fail to explode on release, but denote when impacted by objects later or when they are moved.
Dalya Farran, spokeswoman for the United Nations Mine Action Co-ordination Centre in southern Lebanon (MACC), said: "We don't know exactly how many [cluster bombs] the Israeli forces dropped, but we know they dropped a few million."
Cluster bombs have killed more than 30 people since the war ended in August 2006, mostly civilians, according to MACC figures. More than 200 others have been injured, with some people losing limbs as a result.
Farran said international clearance teams, working with the Lebanese army and the United Nations Interim Forces in Lebanon (Unifitl) have removed about 135,000 bombs already, but as many as one million could remain undetonated.
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