GENEVA — The UN human rights chief on Wednesday slammed the Libyan regime for the alleged use of cluster bombs in Misrata, saying such attacks on densely populated urban areas could be international crimes.

In a statement, UN High Commissioner for Human Rights Navi Pillay "condemned the reported repeated use of cluster munitions and heavy weaponry by Libyan government forces in their attempt to regain control of the besieged city of Misrata."

She noted that one cluster bomb had reportedly exploded a few hundred metres (yards) from a hospital in Misrata while another two clinics were apparently hit by mortar or sniper fire.

"Using imprecise weaponry such as cluster munitions, multiple rocket launchers and mortars, and other forms of heavy weaponry, in crowded urban areas will inevitably lead to civilian casualties," Pillay said.

She warned pro-regime forces that "their orders and actions will be subject to intense scrutiny."

"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," she added.

Libyan strongman Moamer Kadhafi's regime has denied using cluster bombs in clashes with rebels in residential areas following accusations by human rights activists and rebels.

Human Rights Watch said meanwhile that it has examined the munitions, and found that three cluster bomb explosions had occurred over the El-Shawahda neighbourhood in Misrata on April 14.

"I urge the Libyan authorities to face the reality that they are digging themselves and the Libyan population deeper and deeper into the quagmire," Pillay noted.

Pro-Kadhafi forces must halt their siege on Misrata and allow aid through, she said.

The UN rights chief also expressed serious concern about the treatment of journalists by the Libyan regime, pointing out that at least two journalists have been killed and another 16 are missing.

"I am extremely concerned about all those journalists known to be in detention in Libya, or whose whereabouts are unknown, and call on the Libyan government to release them immediately," said Pillay.