"Cluster bombs are a perfectly legal weapon and have an entirely legitimate military role," Hoon said in an interview with BBC radio.

He said the bombs are not used indiscriminately but "in particular circumstances" such as when enemy forces are spread out.

He said that in such situations they could be "safer" than unguided missiles.

Challenged by the BBC interviewer that a reported 30 percent of ordonnance from cluster bombs does not explode and thereby threatens civilians, especially children, Hoon said: "The failure rate for cluster bombs has been progressively reduced and is now said to be in order of some five percent."

And he said British soldiers return to battlefields to "make those bomblets safe."

British campaigners had Thursday slammed the use in Iraq of cluster bombs, which they said kill or maim scores of civilians.

Leading the condemnation was the charity set up to commemorate the late Princess Diana, who lent her name to the campaign against landmines.

"It's appalling that, despite the well-documented problems with cluster weapons, the US and UK are dropping them on Iraq," said Andrew Purkis, chief executive of the Diana, Princess of Wales Memorial Fund.

Cluster bombs frequently killed civilians, added Richard Lloyd, director of British group Landmine Action, pointing to a US attack on the central Iraqi town of Hilla which reportedly killed up to 33 civilians on Tuesday.

On Thursday, British commanders in the Gulf denied using artillery-fired cluster weapons against the southern city of Basra, but confirmed they were being used against Iraqi forces.

Cluster munitions, which can either be dropped from aircraft or fired as shells, split up into a series of smaller "bomblets" which spread out over a wide area and are devastatingly effective against tanks, artillery and troops.

However, often some bomblets do not explode on impact -- the usual failure rate is at least 10 percent, experts say -- and the half-buried explosives remain a serious danger to local people long after the conflict is over.

Campaigners against the weapons say they contravene the Geneva Conventions on conduct during warfare because they cause "unnecessary harm," although this view is disputed.

SPACE.WIRE