Forty-six nations, including the UK, have pledged to work towards a new treaty banning cluster bombs.
US forces have used cluster bombs in Afghanistan
At the end of a two-day conference in the Norwegian capital, Oslo, the countries signed a declaration committing themselves to a ban.
They aim to prohibit by 2008 the use, production, transfer and stockpiling of cluster munitions that cause unacceptable harm to civilians.
The US has rejected any ban, saying the weapons have a place in its arsenal.
Negotiations toward a ban will now take place in a series of meetings over the next year.
They will be held in Peru, Austria and Ireland.
"We are now ready to move ahead towards an international ban on cluster munitions," said Norway's foreign minister Jonas Gahr Stoere.
Campaigners had feared the UK, which has used cluster munitions in Kosovo and Iraq, would step back from committing itself to a new treaty by 2008.
"The UK, which has used so many cluster bombs in the past, showed real leadership and agreed to join a fast-track process to negotiate a ban on cluster bombs that cause unacceptable harm to civilians," said Simon Conway, director of the lobby group Landmine Action.
Cluster bombs spread many explosive bomblets over a wide area
Japan, Romania and Poland refused to sign up to the Oslo declaration. But key nations such as the United States, Russia and China did not attend the conference.
US State Department spokesman Sean McCormack said: "We... take the position that these munitions do have a place and a use in military inventories, given the right technology as well as the proper rules of engagement".
He said the US military had made technical improvements to its own cluster bombs and looked closely at how they were used.
Norway launched an initiative to push for a ban on cluster bombs last November, after some signatories to the UN Convention on Conventional Weapons (CCW) blocked a proposal to open negotiations to include the weapons.
The convention seeks to protect military troops from inhumane injuries and prevent civilians from accidentally being wounded or killed by certain types of arms.
Anti-cluster bomb campaigners claim they endanger civilians because they spread sub-munitions or "bomblets" over a wide area, increasing the risk of civilian casualties.
The charity Handicap International estimates that 98% of those killed and injured by the weapons are non-combatants.
They also say cluster bombs leave a large number of unexploded "duds" which continue to kill and maim long after a conflict has ended. But some military chiefs argue that cluster bombs are highly effective weapons, particularly for attacking moving targets.
They claim banning them would put troops at a disadvantage on the battlefield and would require the use of alternative weapons which are likely to cause far more collateral damage.
Campaigners say the Oslo conference marks a crucial first step towards bringing about an international ban on cluster bombs.
They say it would stigmatise the weapons and put moral pressure on countries which do not sign up not to use them, as the Ottawa treaty outlawing the use of anti-personnel landmines has done.
But without the support of key powers such as the US, Russia and China, says the BBC's Stuart Hughes, the credibility of any new treaty remains open to debate.