A fresh hail of government rockets crashed into Misrata on Friday after Western 'allies' denounced a "medieval siege" of the city and vowed to keep bombing Muammar Gaddafi's forces until he stepped down.
A local doctor told Al Jazeera at least eight people died and seven others were wounded in the second day of intense bombardment of Misrata, a lone rebel bastion in western Libya.
Residents told the television network at least 120 rockets hit the city, where hundreds of civilians are reported to have died in a six-week siege.
NATO is split over providing more planes for the mission in Libya.
"It is unthinkable that someone who has tried to massacre his own people can play a part in their future government," the leaders of Britain, France and the United States said in a joint newspaper article on Friday.
Their clear intention to achieve regime change in Libya goes well beyond the terms of a United Nations resolution authorising air strikes to protect civilians.
Gaddafi's daughter Aisha told a rally in Tripoli that demanding his departure was an insult.
In a strongly worded article published on both sides of the Atlantic, British Prime Minister David Cameron, French President Nicolas Sarkozy and US President Barack Obama said leaving Gaddafi in power would be an "unconscionable betrayal."
"So long as Gaddafi is in power, NATO and its coalition partners must maintain their operations so that civilians remain protected and the pressure on the regime builds," they said.
The statement seemed intended to both paper over cracks in the Atlantic alliance and increase resolve to stick with the air campaign despite increasing differences.
France and Britain, the NATO hawks on Libya, have led the air campaign but are growing impatient with lack of commitment and provision of ground strike aircraft from other members.
The leaders said in their article that Gaddafi could play no role in a genuine transition to democracy. "For that transition to succeed, Colonel Gaddafi must go, and go for good."
Aisha Gaddafi told a rally in Tripoli marking the 25th anniversary of American bombing of Gaddafi's compound there: "Talk about Gaddafi stepping down is an insult to all Libyans because Gaddafi is not in Libya, but in the hearts of all Libyans."
On the fluid eastern front in Libya's two-month civil war, rebels said Gaddafi forces advancing from the oil port of Brega had opened fire on the western edge of the insurgent-held town of Ajdabiyah on Friday, killing one of their fighters.
Fighter Mansour Rachid said Gaddafi's forces were spread out in the desert and hard to locate.
France and Britain want to extend air strikes to the government's logistics and decision-making centres, rather than arming rebels, French Defence Minister Gerard Longuet said.
Asked if it was time to send weapons to the rebels, Longuet said: "This is the reason France and Britain want to show our determination, including with strikes on military decision centres in Libya or on logistics depots which today are being spared."
The article by the three Western allies appeared at a time when diplomatic efforts have failed to paper over divisions between NATO allies about how intensively they should prosecute the three-week-old air war, amid increasing stalemate on the ground.
Britain and France complain that other NATO allies have not provided enough fire power to take out Gaddafi's armour and allow the rebels in control of the east to sweep him from power.
The rebels have begged for more air strikes to avert what they say is a potential massacre in Misrata.
NATO planes bombed targets in Tripoli on Thursday, where state television showed footage of a defiant Gaddafi cruising through the streets in a green safari jacket and sunglasses, pumping his fists and waving from an open-top vehicle.
The attack on Misrata on Friday followed intense fire from Russian made Grad rocket launchers into a residential district on Thursday when rebels said 23 people died, mostly women and children. They said more than 200 missiles fell in the port.
"They shelled this area because the port is Misrata's only window to the outside world," a rebel spokesman using the name Ghassan said by telephone.
"The destruction there was huge. I was there and saw for myself," he said, adding that the port had been shut. Thousands of foreign migrants are stranded in desperate conditions in the open in the port.
Aid organisations warn of a humanitarian disaster.
In their article, the US, British and French leaders said Misrata was "enduring a medieval siege as Gaddafi tries to strangle its population into submission".
At a NATO foreign ministers meeting in Berlin, several alliance members rebuffed calls from France and Britain to contribute more to the air attacks.
Al-Qaeda's deputy leader, Ayman Al-Zawahri, has urged Muslims in a video message to fight NATO forces in Libya, according to the SITE monitoring group.