LONDON - More than 100 countries reached agreement yesterday to ban cluster bombs - weapons that human-rights groups deplore but that the United States, which did not join the ban, calls an integral, legitimate part of its arsenal.

British Prime Minister Gordon Brown, whose personal intervention yesterday led to final agreement among representatives of 111 countries gathered in Dublin, called the ban a "big step forward to make the world a safer place."

The Convention on Cluster Munitions, as approved in Dublin, calls on signatories to stop producing and using cluster bombs and to destroy all stockpiles within eight years.

In addition to the United States, Russia, China, Israel, India and Pakistan - all of them major producers or users of the weapons - did not sign the agreement nor participate in the talks.

The weapons consist of canisters packed with small bombs, or "bomblets," that spread over a large area when dropped from a plane or fired from the ground. While designed to explode on impact, they frequently do not. Civilians, particularly children, are often maimed or killed when they pick up unexploded bombs, sometimes years later.

In staying away from Dublin, U.S. officials argued that the talks were not the right forum in which to address the issue and that cluster bombs remain an important part of the country's weaponry.

"While the United States shares the humanitarian concerns of those in Dublin," said Navy Cmdr. Bob Mehal, a Pentagon spokesman, eliminating cluster bombs "from U.S. stockpiles would put the lives of our soldiers and those of our coalition partners at risk."

The U.S. military says that it keeps the weapons in its arsenal as a defense against advancing armies, a strategy closely linked to conventional Cold War approaches to conflict, and that it has not used the bombs since the 2003 invasion of Iraq.

U.S. officials argue that technological advances will ensure that future cluster bombs reliably explode or quickly disable themselves, so they will not become a hazard to civilians later.

Israel carried out the largest recent use of cluster bombs, dropping large numbers on southern Lebanon in its 2006 war with Hezbollah. Many did not explode immediately and have left a lasting humanitarian hazard.

Advocates of the ban said they hoped the agreement, which was supported by rich nations and poor from Scandinavia to Africa, would have the same effect as the 1997 ban on land mines, reducing use of the weapons even among non-signatory countries.

Already, controversy over cluster bombs has led the United States to stop exporting them for now - a law that was enacted this year bars the foreign sale of cluster bombs with less than a 99 percent detonation or disabling rate, conditions that current versions of the weapons do not meet.

And as a matter of policy, the NATO alliance does not use cluster munitions in Afghanistan.

The Dublin meetings were part of a process begun in February 2007 in Oslo.

Read a draft of the treaty on cluster bombs via