Residents of Libya's third largest city, Misurata, continued to ask for help Saturday, as forces loyal to leader Moamer Gaddafi besieged and shelled the city, DPA reported.
Independent human rights groups have said Gaddafi's forces are using cluster bombs to attack the port city.
Government forces have been intensifying pressure on Misurata in response to growing political support to the rebels, one resident said.
"Gaddafi is trying to seize Misurata as soon as possible before any ground intervention by NATO. So the situation will be worse if nothing is done soon," he said in an audio message posted online.
"All the people are against Gaddafi, but he is trying to hold them by force, arms, snipers and by controlling the media," he added.
Despite pressure from NATO, witnesses say that any gathering of people in the western city quickly becomes a target of pro-Gaddafi loyalists.
"We appreciate what NATO has been doing but we there is more than can be done," another resident said.
Misurata, a key city seen as a gateway to Tripoli, has been under attack for around two months, with rebels saying at least 1,000 have been killed there.
The New York-based Human Rights Watch said that troops loyal to Gaddafi used cluster munitions against rebels. At least three grenades with cluster munitions exploded above the contested city of Misurata.
Experts identified the bombs, which were discovered by a New York Times journalist to be cluster munitions produced in Spain, the group said.
Cluster bombs, which eject smaller bomblets that are highly dangerous to civilians, have been outlawed by more than 100 countries in the Convention on Cluster Munitions, which took effect in 2010.
Libya is not a signatory to the convention.
On Friday, families continued to arrive from Misurata to the eastern city of Benghazi. A vessel chartered by the International Organisation of Migration (IOM) picked up 800 migrant workers and other refugees stranded at the western city's port during heavy fighting.
Some 4,000 people still remain stranded in Misurata's port.
Gaddafi's government said earlier this week that any attempt to dock at Misurata's port without the permission of Tripoli would not be guaranteed safety.