The group's call followed a report in the New York daily, Newsday, that US forces had hit areas of Baghdad with cluster ordnance.

"Human Rights Watch believes that the use of cluster munitions in populated areas may violate the prohibition of indiscriminate attacks contained in international humanitarian law," the group said.

The statement said that despite the effectiveness of cluster bombs in achieving certain military objectives, the wide dispersal pattern of their submunitions makes it very difficult to avoid civilians.

Each cluster bomb can contain up to 3,000 bomblets, each of which explodes separately. Bombs of this type were widely used by the United States in the former Yugoslavia and Afghanistan, according to human rights activists.

"These are wholly inappropriate weapons when civilians are around," said Kenneth Roth, executive director of Human Rights Watch. "The reported use of cluster munitions in Baghdad is a serious charge and the Pentagon must respond publicly to it."

SPACE.WIRE