Forces loyal to Muammar Qaddafi have reportedly been firing into residential neighborhoods with cluster bombs, which have been banned by much of the world.
Rebels in Misrata alleged that Qaddafi's forces have been using cluster bombs, which pose particular risk to civilians because they scatter small bomblets over a wide area. New York-based Human Rights Watch reported Friday that such munitions were used, saying its researchers inspected remnants and interviewed witnesses. The New York Times also reported Friday that witnesses confirmed the use of cluster bombs.
Libyan government spokesman Moussa Ibrahim denied the use of cluster bombs. "Absolutely not," he said when asked about the allegations. "We can never do this. We challenge them to prove it."
The newspaper, citing accounts of survivors and physical evidence found on the ground, said such weapons by definition cannot be fired precisely, and thus place civilians lives at great risk when fired into populated areas.
While speaking at a news conference in Berlin, Secretary of State Hillary Rodham Clinton said she was “not aware” of the specific use of cluster or other heavy weapons in Misrata, but said, “I’m not surprised by anything that Colonel Qaddafi and his forces do.
"That is worrying information," Clinton said. "And it is one of the reasons the fight in Misrata is so difficult, because it’s at close quarters, it’s in amongst urban areas and it poses a lot of challenges to both NATO and to the opposition.”
The cluster munitions were visible in use late Thursday in the form of what appeared to be 120-millimeter mortar rounds that burst in the air over the city, scattering high-explosive bomblets below, the New York Times reports.
Misrata has become emblematic of the limits of NATO's air campaign, with the alliance's top military commander saying he needs more precision attack aircraft to avoid civilian casualties in urban combat. President Barack Obama acknowledged in an interview that the two-month-old civil war has reached a stalemate.
After a weeklong flurry of high-level diplomatic meetings in Europe and the Middle East, rebel leaders complained that the international community is not doing enough to keep Qaddafi's troops at bay. In the capital of Tripoli, a government official denied Libyan troops are shelling Misrata and said they are only taking defensive actions.
Friday's fighting in Misrata — even as a NATO foreign ministers meeting in Berlin debated handling of the Libya air campaign — highlight rebel worries that international intervention won't come fast enough or will be ineffective.
"Time is critical, especially for the people in the west part of the country, especially in Misrata," said Mustafa Gheriani, a spokesman for the rebels who seized much of eastern Libya from Qaddafi at the start of the war. "Is there something else on the diplomatic ground that they know that we don't to put more pressure on Qaddafi? The guy is still shelling and killing and it makes no difference to him."
Rights groups have warned that the situation in Misrata, Libya's third-largest city, is dire after 50 days of siege by Qaddafi's troops. Hospitals are unable to cope with growing numbers of casualties, including many shrapnel injuries.
In Friday's assault, a helicopter circled over Misrata for several hours, apparently spotting targets for artillery. Pro-Qaddafi forces bombarded the city with fire from tanks, artillery and rockets, a resident said.
"We've been hearing explosions all day," said the resident, who spoke on condition he be identified only by his given name, Abdel-Salam, for fear of retaliation. Abdel-Salam said the shelling continued until nightfall, portraying the assault as the heaviest since the start of the siege.
Qaddafi's men are in control of the city center, while the rebels are clinging to positions in the port area. Al-Jazeera satellite TV showed video of two armored vehicles parked in a debris-filled street of Misrata.
Qaddafi loyalists have been firing randomly from their positions in the city, forcing people to leave their homes, said a city resident. Once a building is empty, it is being taken over by government troops, said the resident, who spoke on condition of anonymity for fear of retribution. He said government troops have also targeted groups of civilians in the streets, including people standing in line outside a bakery.
He said rebel-held neighborhoods are becoming increasingly crowded. "Now you can find houses with more than 10 families in one house," he said.
The Associated Press contributed to this report.