There have been reports of fresh clashes between Colonel Gaddafi's forces and Libyan rebels in the eastern town of Ajdabiya - as leaders from the African Union prepare to meet in Tripoli.
There are reports four rebels have been killed during the fighting.
It follows fierce fighting in Libya's third city of Misratah. A spokesman for the rebels said at least 30 people have been killed.
Defence Secretary Liam Fox said the Nato operations were working but warned not to be complacent about Gaddafi's capabilities.
"The truth is that the Gaddafi regime is quite well dug in," he told Sky News.
"It's a regime that doesn't care about the wellbeing of its civilian population.
"It cares nothing for anybody but its own survival."
Nato aircraft destroyed 15 of Col Gaddafi's tanks near Misratah and another two near the eastern town of Brega, where Government forces also claimed to have shot down two rebel helicopters.
Nato's commander of Libyan operations said the alliance had destroyed "a significant percentage" of his armoured forces in the past 24 hours as well as ammunition stockpiles east of the capital, Tripoli.
Canadian Lieutenant General Charles Bouchard also accused Col Gaddafi's troops of using civilians as human shields to deter Nato forces from attacking them. Similar charges have been made by other Western commanders.
"We have observed horrific examples of regime forces deliberately placing their weapons systems close to civilians, their homes and even their places of worship," Lt Gen Bouchard said in a statement.
"Troops have also been observed hiding behind women and children. This type of behaviour violates the principles of international law and will not be tolerated."
African Union mediators have renewed their appeal for "an immediate end to all hostilities" and proposed a transition period to adopt reforms.
The panel of five African leaders, headed by Mauritanian President Mohamed Ould Abdel Aziz, decided to go along with a roadmap adopted in March which calls for an end to hostilities, "diligent conveying of humanitarian aid" and "dialogue between the Libyan parties", it said in a statement.
They are due to meet Col Gaddafi in Tripoli and leaders of the rebellion in Benghazi later.