NATO "is letting the people of Misrata die every day," Yunis told a news conference in the rebel stronghold of Benghazi.

"If NATO waits one more week, there will be nothing left in Misrata," he added.

"What is NATO doing" he asked. "They are bombing here and there," while the city's residents are faced with "extermination".

The last rebel-held bastion in the west of Libya, Misrata has been pounded by forces loyal to Moamer Qadhafi for more than 40 days.

NATO's chief of allied operations, Brigadier General Mark van Uhm, said earlier Tuesday that the alliance was doing all it could to protect civilians in the city, after a Turkish aid ship brought out scores of wounded who told was harrowing tales of the bombardment of residential areas by loyalist artillery.

"Misrata is a number one priority because of the situation on the ground over there," the NATO chief of allied operations said.

"We have confirmation that in Misrata tanks are being dispersed, being hidden, (and) humans being used as shields in order to prevent NATO sorties to identify targets," he said.

Doctors said last week that 200 people had been killed there since the fighting began, a figure that is likely to have risen in recent days.