These indiscriminate killers leave their deadly legacy from Libya to Lebanon

In early April, as troops loyal to the Libyan dictator Muammar Gaddafi laid siege to the town of Misrata, those trapped inside the port city noticed that their opponents had begun to use a previously unseen artillery round.

Libya's third-largest city had been seized by rebel forces in early February but, two months later, it was surrounded, cut off from the Benghazi rebels after a series of successful counter-attacks by Gaddafi's troops. The Libyan leader was determined to retake the city and had already shelled the area, despite the presence of tens of thousands of civilians.

As the battle intensified the cluster rounds came out. Waleed Srayti, a local inhabitant, later described to Human Rights Watch what he saw.

"A big battle was going on in Tripoli Street at the vegetable market," he said. "I heard a noise and about nine to 10 things started popping out of the sky over the market. I just saw the pops in the air."

What Mr Srayti had encountered were MAT-120s, a Spanish-made mortar shell which opens in mid-air and disperses 21-bomblets over a wide area. When those bomblets hit their target – be it a vehicle, a home or a person – they detonate, spraying out a slug of white-hot molten metal that can penetrate a tank's armour. The hospitals soon filled up with civilians and rebel soldiers exhibiting horrendous burns.

Most countries – including Britain – have now banned cluster weapons, recognising that they are inherently indiscriminate. But the sad reality remains that plenty of countries still feel it is perfectly acceptable to use such weapons. Spain – one of the 108 signatories to the Convention on Cluster Munitions – destroyed its stockpile of 1,852 MAT-120s back in 2008, but by then it had already sold an undisclosed number of mortar rounds to Gaddafi.

Persuading despots to abandon their own stockpiles is difficult considering countries like the United States, Russia and China – the main manufacturers of cluster bombs – have refused to sign the treaty.

But Libya is not the only country to have recently resorted to cluster bombs. Earlier this year the Cluster Munition Coalition announced that Thailand had fired cluster shells at a Cambodian village during its brief but violent flare-up with its neighbour. It is thought as many as 15,000 sub-munitions still remain in an area 20km from the Preah Vihear Temple including US-made M42, M46 and M85 sub-munitions.

All of which pales in comparison to Israel which, in the dying stages of its 2006 conflict with Hezbollah, dropped more than four million bomblets over southern Lebanon in what the UN described as "a flagrant violation of international law". An estimated 40 per cent failed to detonate leaving a deadly legacy. In the past five years more than 50 people have been killed by unexploded bombs, with nearly 400 injured.