This type of bomb was used by Nato in Kosovo conflict
The modern cluster bomb dates back to the 1960s and was extensively used in Vietnam, the Gulf War and the recent conflict in Kosovo.
A typical cluster bomb is made up of a container or dispenser - essentially a bomb-shaped cylindrical casing - which carries a large number of sub-munitions or bomblets to the target area.
There are a huge variety of cluster bombs manufactured by a number of countries.
But they work on the same principle: after being dropped from an aircraft, the container opens, either scattering or ejecting the sub-munitions over a large area.
The sub-munitions can be of a variety of types:
Cluster bombs have the great advantage that they can be used against a variety of targets covering significant areas, rather than, for example, pin-pointing individual armoured vehicles.
The US used a staggering number of such bombs in south-east Asia. Pentagon estimates suggest that some 285 million sub-munitions were dropped on Cambodia, Vietnam and Laos.
One of the great problems with these weapons though is the tendency of many of the bomblets to fail to explode - a point highlighted by the UK Working Group on Landmines' study.
This is especially the case when the weapons are dropped from medium or high altitude, when the bomblets tend to drift in the wind and can land a long way from the intended target.
The fact that some bomblets may be brightly coloured and appear interesting to children also causes many accidents in the aftermath of conflicts.
Air warfare experts insist that the bombs still have a useful role to play - especially in a full-scale war.
But the very limited nature of many recent conflicts has led many western air forces to seek more accurate, less indiscriminate weapons, which would be less likely to present a continuing danger once the fighting is over.