NATO warplanes destroyed 11 regime tanks on the road to the eastern Libyan town of Ajdabiya and another 14 tanks near Misrata in the west on Sunday, an alliance official told AFP.

"As of noon today, NATO air strikes have taken out 11 tanks on the road to Ajdabiya and strikes will continue through the day and tonight," the official said on condition of anonymity.

"Clearly the situation in Ajdabiya is desperate and Gaddafi forces are attacking the town with heavy weapons," the official said.

Loud explosions rocked the battleground town of Ajdabiya for a second day Sunday as rebel fighters advanced cautiously after suffering a major reverse at the hands of loyalists.

Another 14 regime tanks were destroyed near Misrata, the rebels' last major bastion in the west, besieged by Colonel Muammar Gaddafi's forces for more than a month, the NATO official said.

The alliance had already taken out 15 tanks near Misrata on Friday and Saturday, bringing to 29 the total number of tanks destroyed around Libya's third largest city in the past three days.

Western strikes against regime forces began on 19 March under a UN mandate to protect the population after Gaddafi unleashed his security forces to violently put down pro-democracy protests.

The United States handed control of the operation to NATO on 31 March.

Libyan rebels have criticised NATO in recent days, accusing the alliance of failing to protect the population in Misrata.

But NATO says it is picking up the pace of air strikes.

Lieutenant General Charles Bouchard, head of Operation Unified Protector, said Saturday that warplanes had destroyed ammunition stockpiles and several armoured vehicles in the previous 24 hours.

NATO aircraft struck ammunition stockpiles east of Tripoli that were being used to resupply regime forces that were shelling innocent civilians in Misrata, the alliance said.

"In addition to hitting their supplies, our aircraft successfully destroyed a significant percentage of the Libyan government’s armoured forces," Bouchard said in a statement from his headquarters in Naples, Italy.

"Some of these armoured forces also were involved in the indiscriminate shelling of Misrata," he added.

The mission to protect civilians was being made increasingly difficult by the use of women and children as human shields by government troops striking at rebel fighters in the heart of communities, NATO said.

"We have observed horrific examples of regime forces deliberately placing their weapons systems close to civilians, their homes and even their places of worship," said Bouchard.

"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," he added.