BREGA, Libya - (AP) - Libyan government forces unleashed awithering bombardment of rebels outside a key oil town Tuesday asan Obama administration envoy met with the opposition leadership inits de facto capital, a possible step toward diplomaticrecognition.

NATO said nearly a third of Libyan leader Moammar Gadhafi'sheavy weapons have been destroyed. But the alliance said Gadhafi'sforces had changed tactics in the besieged western city of Misrataby moving tanks and other heavy equipment to civilian areas toprevent pilots from targeting them.

A doctor in Misrata corroborated that, saying Gadhafi's forceshave been placing heavy weapons near civilians there for the pasttwo weeks.

"They snuck their anti-aircraft weapons and tanks into thecity. They are between the apartment buildings and the trees,"said the doctor, who spoke on condition of anonymity for fear ofreprisals. "They disguise their equipment on the big agriculturaltrucks that the farmers use outside of town. They bring in mortarswith civilian cars."

The opposition has controlled much of the eastern half of Libyasince early on in the uprising that began in February. Misrata isone of two major cities in the west that have also risen up againstGadhafi's regime, which has responded with a brutal crackdown wagedover weeks of battles.

The other front is on a coastal road leading out of the rebelstronghold city of Benghazi in the east toward the capital Tripoliin the west. Gadhafi loyalists and opponents have fought atug-of-war for weeks on the road, with a few main towns and oilports changing hands repeatedly. Though Gadhafi's forces arestronger, NATO airstrikes have helped the rebels hold back anonslaught on the east.