Tanks and troops loyal to Moamer Kadhafi swept through rebel-held Misrata on Tuesday, a rebel spokesman said as a doctor in Libya's third city put the death toll at 142 since March 18.
Kadhafi troops indiscriminately shelled Misrata, 214 kilometres (132 miles) east of Tripoli, and are preparing for a "massacre," the rebel spokesman told AFP by telephone.
"Misrata is in danger. The criminal forces are advancing on the city and the tanks are firing shells indiscriminately," he said, asking that his name be withheld.
"The massacre that was avoided in Benghazi thanks to the intervention of coalition forces will be carried out in the Misrata," the spokesman said.
The rebel stronghold of Benghazi is located 810 kilometers (503 miles) east of Misrata along the Mediterranean coast.
Western coalition forces launched a campaign on March 19 to enforce a UN no-fly zone in Libya and to protect civilians under attack and pounded Kadhafi forces in and around the rebel stronghold.
"Unlike what happened in Benghazi, coalition warplanes did not hit (Kadhafi) tanks that are already inside Misrata to avoid civilian casualties," the spokesman said.
He also spoke of a "humanitarian catastrophe" while a city doctor speaking separately to AFP said that at least 142 people were killed and more than 1,400 others injured since Kadhafi loyalists began hammering the city on March 18.
"We have had 142 dead since March 18," including four people who died on Monday, said the doctor, also speaking on condition of anonymity.
"We can't keep count anymore of the wounded but it is clearly more than 1,400, including 90 in a serious condition," he added.
He said that a Turkish boat was expected to dock at Misrata port later Tuesday to evacuate at least 50 wounded.
Rebels earlier said that a hospital ship was due in Misrata.
"It is a floating hospital that is being escorted by NATO that was delayed," a rebel spokesman, Shamsiddin Abdulmolah, said.
He said the vessel's arrival came two days after that of another ship in Misrata carrying humanitarian supplies, including food, milk, flour and other staples.
Abdulmolah could not provide further details about either ship, or which organisation chartered them.
Journalists in Tripoli on Monday were bussed to the outskirts of Misrata by Libyan government officials, to witness a pro-Kadhafi demonstration as it was broadcast live by Libyan state television.
They said they were not taken into the city, but it was clear that widespread destruction and fighting had occurred, and black smoke hung over the area.
Rebels have said that Kadhafi forces expelled more than 5,000 families from their homes in the western part of the city.
"Hundreds of families have found refuge in schools and mosques. The situation is very dangerous, very delicate," a rebel spokesman said.
He said Kadhafi forces were controlling the northwestern part of Misrata.
The Libyan foreign ministry said on Monday that its troops completed an offensive against Misrata and that "calm" reigned once again in the strategic city.
"Anti-terrorist units have ceased firing on armed terrorist groups who have committed all manner of acts of terrorism against the population of Misrata and disrupted their lives," a foreign ministry statement said.
"The town of Misrata currently enjoys an atmosphere of safety and calm and its public bodies are once again able to serve the public normally," said the statement carried by the official news agency Jana.
It was not clear however if Kadhafi forces were in full control of Misrata or just part of it.