Mohammad Al Atrash, eight, rests after undergoing a CT scan at a hospital The Libyan government\'s reported use of cluster munitions and heavy weapons in Misrata has caused substantial civilian casualties and may amount to crimes under international law,

the United Nations said Wednesday. UN High Commissioner for Human Rights Navi Pillay called for a halt to the siege of Misrata and condemned the attacks, including a cluster bomb said to have exploded last week several hundred metres from the hospital in the west Libyan city.

\"Under international law, the deliberate targeting of medical facilities is a war crime and the deliberate targeting or reckless endangerment of civilians may also amount to serious violations of international human rights law or international humanitarian law,\" Pillay said in a statement.The rebels accuse forces supporting Libyan leader Muammar Gaddafi of using cluster bombs. The US-based Human Rights Watch said last week government forces had fired the weapons into residential areas of Misrata and it had found remnants.

The Libyan government, which denies shelling civilians, has also denied this allegation. At least two medical clinics in Misrata are reported to have been hit by mortar rounds or sniper fire, according to Pillay.