During the war, Israel dropped more than four million cluster bombs on south Lebanon in violation of international humanitarian law.
Since 2006, hundreds of civilians have been killed by the delayed detonation of these weapons.
"Eight children, aged between six and eight years old, were wounded when a cluster bomb left over from the 2006 war exploded in the town of Zebqin, in the region of Tyre," the security official said.
"One child was wounded in the head and is in critical condition in the operating theatre," said an employee at the Lebanese-Italian hospital in Tyre, where the children were taken.
"We were having a picnic next to a river in Zebqin and on the way back, my friend stepped on a device that exploded, and we were all hit," six-year-old Hussein Bazzi told.
Since 2006, more than 400 people, 90 per cent of them civilians and a third under the age of 18, have been killed by cluster bombs. Dozens more have been handicapped.
Nearly 70 per cent of bomb-infested land has been cleared, but a lack of funding has prevented the dismantling of other bombs scattered throughout villages in the south.
The munitions contained in cluster bombs, if they do not explode immediately, are still able to kill and mutilate long after they have been dropped.
Israel is not a signatory to the 2010 Convention on Cluster Munitions, which bans the development and use of these bombs.