Figures from the Lebanese military show that eight people, including several children, have been killed and a further 38 wounded by cluster bomb explosions since the start of a ceasefire on August 14 to end a month-long conflict between Israel and Hezbollah.
On Wednesday, three Lebanese bomb disposal specialists were killed by a cluster bomb in the village of Tebnin, some 15km from the Israeli border.
Dalya Farran of the UN Mine Action co-ordination centre in south Lebanon declared it an "emergency situation".
Hundreds of Israeli artillery shells containing nearly 200 explosive rounds each were fired into southern Lebanon during the fighting, landing in villages and towns dozens of kilometres beyond the border.
Each time a shell lands, hundreds of bomblets burst from it, creating a huge area ridden with dangerous shrapnel.
"The Israelis were using Vietnam-era stock with an extraordinarily high dud rate. We've seen some ordnance that was dated March 1973"
Human Rights Watch
But the UN estimates that a dangerously high percentage of these failed to explode, leaving their targets strewn with potential death traps.
Farran said that according to the most recent data, 185 cluster bomb strikes have been found so far by assessment teams who have the additional pressure of displaced people seeking to return to their stricken villages.
"Not all of these, a majority maybe, failed to go off," Farran said.
She said those intact bomblets are hard to find amid the rubble, and when they are spotted, "people assume that because of their small size that they are harmless".
The result, according to a military analyst with Human Rights Watch, Marc Garlasco, are "minefields in peoples' homes".
"The Israelis were using Vietnam-era stock with an extraordinarily high dud rate. We've seen some ordnance that was dated March 1973," Garlasco said following a week-long tour through the south where "whole villages have been contaminated" by bombs.
"There are kids playing with them and getting hurt, killed."
In a fact sheet issued earlier in the week, the UN urged parents to be especially vigilant for unexploded ordnance.
As part of a large public education campaign, the Lebanese army has dropped 100,000 leaflets and distributed 10,000 posters at checkpoints, and radio and television channels have aired warnings against the dangers of unexploded munitions.