The unexploded bombs, mostly sub munitions, landed indiscriminately in civilian areas, the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said on Sunday.
The OCHA said it had recorded 608 areas where cluster munitions landed, "with more locations being identified every day".
UN humanitarian chief Jan Egeland in August said it was "completely immoral ... that 90 per cent of the cluster bomb strikes occurred in the last 72 hours of the conflict when it was clear a UN resolution was about to bring about a ceasefire".
Lebanese police said that 21 people had been killed by the bomblets, including 16 civilians and five army bomb-disposal experts, since the 34-day conflict ended on August 14.
The Lebanese army says that there are "possibly around one million" unexploded bombs scattered around the south.
The Israeli newspaper Haaretz said the Israeli army fired at least 1.2 million rockets into Lebanon during the conflict.
The cluster bombs used by Israel contain hundreds of bomblets which are dispersed over a large area. Those that do not explode on impact turn into lethal anti-personnel mines.
Cluster munitions are controversial, as human-rights groups say they cause indiscriminate civilian casualties over large areas.
Chris Clark, head of a UN mine action group in southern Lebanon, said last month that tactical maps handed over by Israeli forces were "absolutely useless" in clearance efforts with regard to landmines that were placed by Israeli troops in the 1980s.
Lebanese school start dates will be delayed until mid October, due to the ongoing repairs of damaged buildings caused by the recent Israeli shelling of Lebanon, said Khaled Kabbani, the Lebanese minister of education.
"The government is working hard to return all students to their schools by October 16."
According to government estimates, around 50 schools were destroyed and 300 damaged by the conflict.
The government estimates reconstruction costs to reach $70 million.
Saudi Arabia, Kuwait and the United Arab Emirates, as well as the UN children's agency Unicef, have been helping in the rebuilding process and handing out books and school bags to children.