WASHINGTON (Reuters) - A proposed global ban on cluster bombs could jeopardize U.S. participation in joint peacekeeping and disaster relief operations around the world, a senior U.S. official said on Wednesday.

Representatives of over 100 nations are meeting in the Irish capital Dublin to hammer out an agreement against use of cluster munitions, although the United States, China and Russia are not participating. Critics say such munitions are unreliable and indiscriminate.

But Stephen Mull, acting U.S. assistant secretary of state for political-military affairs, said the weapons have a “certain military utility.”

He told reporters the proposed ban being discussed could “criminalize” joint military operations between countries that signed the ban and those that did not.

“For example, if the convention passes in its current form, any U.S. military ship would be technically not able to get involved in a peacekeeping operation like disaster relief, or humanitarian assistance, as we are doing right now in the aftermath of the earthquake in China and the typhoon in Burma, not to mention everything we did in southeast Asia after the tsunami in December of 2004,” Mull said.

“And that’s because most U.S. military units have in their inventory these kinds of weapons,” he said.

Cluster munitions open in mid-air and scatter as many as several hundred “bomblets” over wide areas. They often fail to explode, creating virtual mine fields that can kill or injure anyone who comes across them -- often curious children.

U.N. Secretary-General Ban Ki-Moon told the delegates in Dublin earlier this week that the use, development, production, stockpiling and transfer of cluster bombs should be prohibited.

The talks in Dublin are part of the Oslo process, launched by Norway several years ago to prepare a treaty on an international ban of cluster weapons. The meeting has been undermined by the absence of the United States, China and Russia, which oppose a global ban.

Mull said the United States thought it would be impossible to ban cluster bombs. A more effective solution would be a technical fix, dealing with the timing of the fuse mechanism so that the weapons’ viability is limited, he said.

OTHER SOLUTIONS?

Washington would pursue such a solution via another international forum, called the Convention on Certain Conventional Weapons (CCW), which gathers all the major producers and consumers of cluster weapons, Mull said. The next meeting is in Geneva in July.

The United States has not used the weapons since the first year of the Iraq war in 2003, Mull said. He said Washington was not currently exporting cluster bombs because a law Congress passed last year said cluster munitions with less than a 99 percent reliability rate could not be sold abroad.

The bombs can be dropped from aircraft or fired in missiles or artillery shells and have been used in conflicts including Iraq, Afghanistan, Vietnam, the Balkans and in Israel’s 2006 war with Hezbollah guerrillas in southern Lebanon.

Mull said the United States might need to use them to help its allies. He said the bombs would be very effective in terms of stopping an advancing army, such an invasion of South Korea or an invasion of Lebanon by Syria.

A United Nations commission said Israel did not limit assaults to military targets in the 2006 war, but an Israeli army probe said Israel did not break international law.

Mull said U.S. officials had consultations with the Israelis and “we understand that they are introducing reforms so those sorts of mistakes don’t happen again.”