The alliance says Qaddafi's forces have changed tactics in the besieged western city of Misrata, moving tanks and other heavy equipment into civilian areas to prevent pilots from targeting them.
A doctor in Misrata backs up the accusation, saying anti-aircraft guns and tanks have been stationed "between the apartment buildings and the trees." He says military equipment is being disguised on the big agricultural trucks that Libyan farmers use, while mortars are being brought into the city in civilian cars.
NATO says three-quarters of yesterday's scheduled strike missions had to return without dropping their bombs or launching their missiles because Qaddafi loyalists made it too difficult for pilots to distinguish between civilians and regime troops.
Misrata is one of two major cities in western Libya that have risen up against
Meanwhile Tuesday, a U.S. envoy to the Libyan opposition was in the rebel stronghold of Benghazi for talks with opposition leaders, a U.S. official said.
The envoy, Chris Stevens, was meeting with members of Libya's Transitional National Council to get a better idea of who they are, what they want and what their needs and capabilities are, the official said. His visit could pave the way for U.S. recognition of the council as Libya's legitimate government although no decision is imminent, the official said.
Stevens was the No. 2 at the U.S. embassy in Tripoli until the mission was shuttered in February amid escalating violence. He will be discussing humanitarian and possible financial assistance to the opposition, the official said. The official spoke on condition of anonymity pending an announcement of the visit by the White House on Tuesday.