Libya: Gaddafi accused of firing cluster bombs on Misurata (VIDEO)

As Libya's rebel forces reportedly advanced once again to the strategic oil town of Brega thanks to four days of air strikes by NATO, troops loyal to Libya's defiant leader Muammar Gaddafi were accused of firing cluster bombs into civilian areas of the front line city Misurata.

Cluster bombs are outlawed by much of the world because they cannot be fired precisely and therefore pose a great risk when used in densely populated civilian areas.

Human Rights Watch (HRW) said it saw at least three of the controversial devices — which scatter a number of smaller bomblets over the target — explode over the al Shawahda neighborhood on April 14.

In addition to cluster bombs, Gaddafi's forces are reportedly using other indiscriminate weapons like GRAD rockets against the civilians of Misurata. A rebel spokesperson told Reuters that Gaddafi's forces fired at least 100 GRAD rockets into an industrial area of the city Saturday, although no casualties were reported.

An investigation by the New York Times, meanwhile, found that 120-millimeter mortar rounds burst in the air over the city of Misurata late Thursday night, signaling the use of cluster munitions.

"Remnants of expended shells, examined and photographed by The New York Times, show the rounds to be MAT-120 cargo mortar projectiles, each of which carries and distributes 21 smaller submunitions designed both to kill people and penetrate light armor," it states.

However, Libyan government spokesman Moussa Ibrahim rejected claims that Gaddafi's forces had used cluster bombs.

"I challenge them to prove it," he said, Sky News reported. "To use these bombs, the evidence would remain for days and weeks, and we know the international community is coming en masse to our country soon, so we can't do this."

Libya has invited the U.N. children's fund to visit Misurata, he said, adding that a Red Crescent and Red Cross team was due to visit Saturday.

President Barack Obama, British Prime Minister David Cameron and French President Nicolas Sarkozy published a joint newspaper article vowing to continue the NATO military campaign until Gaddafi left power. According to Reuters, they acknowledged their aim of regime change went beyond protecting civilians, as allowed by a U.N. Security Council resolution, but said Libyans would never be safe under Gaddafi.

Explosions that appeared to be from new NATO air strikes could be heard Saturday in the oil town of Brega, according to the Associated Press. Anti-Gaddafi forces claimed to have reached the outskirts of the town, which has already changed hands half a dozen times since fighting began in early March.

And rebel forces have reportedly maintained their positions around the city of Ajdabiya, about 30 miles to the east.

Doctors in Misurata, meanwhile, said Gaddafi's offensive in Misurata had killed about 600 people and left more than 3,000 injured, according to the Independent.

The area where HRW witnessed the use of cluster munitions is near the front line in the fighting which has raged for six weeks. HWR condemned the use of the cluster munitions Friday, saying they posed a "grave risk to civilians."

"It's appalling that Libya is using this weapon, especially in a residential area," Steve Goose, arms division director at HRW, said in a press release. "They pose a huge risk to civilians, both during attacks because of their indiscriminate nature and afterward because of the still-dangerous unexploded duds scattered about."

Misurata has become one of the fiercest battlegrounds of the almost two-month long fight for control of Libya.

"As the last rebel holdout in the west, Misurata has become a symbol of defiance, a place of resilience and determination which is bloody but unbowed despite the weeks of fierce pounding," a report from Misurata in the Independent states. "The defiance of this opposition enclave, so close to the capital, seemed to have enraged Colonel Gaddafi's regime as it lashed out repeatedly in frustrated fury."

Earlier Friday, state television broadcast images of Gaddafi, standing through an open car sun roof — his fist pumping the air — as the sports utility vehicle sped through the streets of Tripoli pursued by supporters. The impromptu parade came as powerful explosions rocked the city.