Muammar Gaddafi's forces attacked two western Libyan towns, killing dozens, while rebels have been pinned down in the east of the country.
Gaddafi, in his first appearance since the bombing campaign began, has vowed to fight on.
'We will be victorious in the end,' he told crowds at his Tripoli compound who have volunteered to be human shields.
Meanwhile, NATO has tried to resolve a dispute over who should lead the Western air campaign.
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Anti-Gaddafi rebels have struggled to capitalise on the ground on the air strikes against Libyan tanks and air defences.
In the latest fighting today, Gaddafi's tanks shelled the rebel-held western town of Misrata and casualties included four children killed when their car was hit.
Residents and doctors in the city said the death toll for yesterday alone had reached 40.
Residents painted a grim picture of the situation in Misrata, under siege by Gaddafi forces for weeks, with tanks in the city centre and doctors operating on people with bullet and shrapnel wounds in hospital corridors.
'The situation here is very bad. Tanks started shelling the town this morning,' a resident called Mohammed told Reuters news agency by telephone from outside the city's hospital.
He added: 'Snipers are taking part in the operation too. A civilian car was destroyed killing four children on board.'
Gaddafi's forces are also trying to seize the western rebel-held town of Zintan near the Tunisian border in an attack using heavy weapons.
One resident said ten people were killed today and most people fled to seek shelter in nearby mountain caves.
Rebels in east Libya are stuck just outside Ajdabiyah and have made no advance on the strategic town.
Libya's deputy foreign minister said the army was not conducting offensive operations, only defending itself.
US airmen rescued after jet crashes
In the first apparent air force loss of the campaign, a US F-15E crashed in Libya overnight, but the US military said its two crew members were rescued.
It said the crash was probably caused by mechanical failure and not hostile fire.
Explosions and anti-aircraft fire have been heard across Tripoli for three nights and state television reported several attacks by the 'crusader enemy'.
The US military said that 20 Tomahawk missiles were fired at Libyan targets overnight.
'Significant reduction' in US flights over Libya
US President Barack Obama has said he expects 'clarity' on the future command structure of allied military operations in Libya 'over the next several days'.
He said: 'I would expect that over the next several days we will have clarity and a meeting of the minds of all those who are participating in the process.'
Mr Obama also said has already been a 'significant reduction' in US flights over Libya.
The US President discussed the Libya operation with British Prime Minister David Cameron and both men agreed that 'substantial progress' has been made in implementing UN resolution 1973.
Meanwhile, US Secretary of State Hillary Clinton has said the US believes Gaddafi may be exploring exile options, but it is unclear if he is serious.
