NATO moved toward assuming command of Western military intervention in Libya on Thursday after days of wrangling, and French warplanes destroyed a Libyan plane and bombed an air base on the sixth day of allied attacks on forces loyal to Moammar Gaddafi.

Turkish Foreign Minister Ahmet Davutoglu told reporters in Ankara that a “compromise has been reached in principle” on transferring control of the Libyan operation from an ad hoc U.S.-led coalition to formal NATO command. The arrangement was hammered out in a conference call among U.S. Secretary of State Hillary Rodham Clinton and her counterparts from France, Britain and Turkey. As a NATO member, Turkey had insisted on conditions for NATO’s takeover of the operation.

The transfer from U.S. leadership, sought by President Obama, is expected to take a few days to complete after it is officially approved.

The move comes amid an apparently intensifying campaign of airstrikes and missile attacks that are taking a toll on Gaddafi’s forces but have not relieved the siege of rebel-held Misurata, where a humanitarian crisis is unfolding.

In Benghazi, the de facto rebel capital in eastern Libya, a spokesman for the anti-Gaddafi forces said that loyalist troops in the strategic city of Ajdabiya were trying to surrender.

“We are trying to negotiate with these people in Ajdabiya because we are almost sure that they have lost contact with their headquarters,” said Col. Ahmad Omar Bani, a former Libyan air force pilot. “We received information from freedom fighters in Ajdabiya saying some [Gaddafi] fighters have offered to leave their tanks,” he said, adding that a local imam was helping in the negotiations.

Bani said the opposition is forming a “new army” that will be more organized than the rebels, but he could not say how long that would take.

Earlier Thursday, French fighter jets destroyed a Libyan plane near Misurata and bombed an air base deep inside Libya, as U.S. and British cruise missiles struck targets in and around the capital, Tripoli.

The strikes further pounded the already decimated Libyan air force, but they failed to prevent Gaddafi’s tanks from reentering Misurata overnight and shelling the area around its main hospital, news services reported.

The continued fighting aggravated a humanitarian crisis that doctors in Misurata, Libya’s third-largest city 130 miles east of Tripoli, say has been growing worse.

The transfer to NATO of Operation Odyssey Dawn, as the coalition’s Libyan mission is known, began to take shape when Turkey announced it would not longer oppose the shift, paving the way for the United States to turn over command in the coming days.

Turkey is the only Muslim-majority member of NATO, and the alliance needs all 28 member nations to approve any military action. Davutoglu told Turkish state television Thursday, “Our demands have been met on Libya. The operation will be handed over to NATO.”

Obama has said he intends to turn the mission over to international command in “days, not weeks,” and the announcement of Turkish support apparently allows that to happen over the weekend.

Obama, along with French President Nicolas Sarkozy and British Prime Minister David Cameron, reached a tentative agreement earlier this week for NATO to command the military mission. In addition, a steering committee of NATO and non-NATO members, including Arab countries participating with military aircraft and humanitarian support, has been proposed to provide political guidance for the operation, but it is unclear whether that is still under discussion.

Obama is facing mounting pressure from Congress to explain the Libyan operation, which represents America’s third military front in a Muslim nation. He has sought to play down U.S. participation, saying that the U.S. military would lead the operation’s first phase, particularly in taking out Gaddafi’s air-defense system, and then fall back into a supporting role.

In a Pentagon news briefing Thursday, Vice Adm. William E. Gortney said, “We are going to give up the command position . . . and be participants” in the Libyan operation. he said the United States would “continue to provide predominantly those capabilities we have that are unique,” such as refueling tankers, “ISR [intelligence, surveillance and reconnaissance] platforms” and “some of the interdiction strike packages.”

Gortney said coalition planes are not attacking Gaddafi’s forces inside cities because of the risk of civilian casualties but are focusing on isolating those forces and cutting their supply lines.

Asked about the prospect that more restrictions could be placed on coalition strikes under the new command structure, Gortney said: “I’m not sure how the rules of engagement could be any more restrictive than they already are.”

He said the coalition is using “every tool in our toolkit” to send messages to Gaddafi’s forces telling them to stop fighting or face attack. “They need to cease fighting and either stay in place or abandon their equipment,” he said. To be on the safe side, he suggested, “maybe they ought not use their tank or their armored personnel carrier as a mode of transportation to get home.”

In Tripoli, officials took journalists to a hospital to see the charred and mangled bodies of 18 men they said were victims of Western airstrikes, Reuters news agency reported. A Libyan official said that some of the dead were soldiers killed in an airstrike Wednesday and that some were civilians, but the reporters were not shown any bodies of women or children, and it was not possible to determine whether any civilians were among the dead. The bodies were also shown on Libyan state television.

Rebels in Benghazi said the bodies put on display were victims of Gaddafi’s strikes in towns such as Misurata and Zawiyah and were brought out of refrigeration for propaganda purposes. “You can see on the television, people are holding their noses because of the stench,” said Hasan Modeer, a rebel activist. “These are not fresh bodies.”

Libya says that dozens of civilians have died in the Western airstrikes. U.S. military officials deny that the strikes have killed civilians and say that tank, artillery, rocket and sniper fire by Gaddafi’s forces have killed them.

A French Rafale fighter helping to enforce a U.N.-mandated no-fly zone over Libya destroyed what was identified as a Libyan G-2/Galeb trainer aircraft near Misurata, the Associated Press reported.

The French Defense Ministry later said the Libyan plane breached the no-fly zone and was hit with an air-to-ground missile just after it landed at the Misurata air base. In an account on its Web site, the ministry described the Libyan aircraft as a “warplane” and said it was detected violating the no-fly zone by a coalition AWACS early-warning plane.

French Mirage 2000D and Rafale jets also hit an “isolated” Libyan air base overnight about 155 miles south of the Mediterranean coast, the French military said, without elaborating on the target or the results.

But Libyan Deputy Foreign Minister Khaled Kaim said in Tripoli that a military compound at Juffra, which includes an air base, was bombed before dawn.

Western warplanes and ship-fired missiles struck other targets in Libya overnight, and NATO ships patrolled the coast to block the arrival of weapons or mercenaries hired by Gaddafi.

More than a dozen Tomahawk cruise missiles, fired late Wednesday and early Thursday from U.S. and British ships in the Mediterranean, hit targets air-defense sites in Tripoli and south of the capital, AP reported, while other attacks were carried out against an ammunition bunker near Misurata, Gaddafi forces south of the rebel capital of Benghazi and tanks, artillery and helicopters on the ground at a coastal airfield.

At the same time, international aid organizations scrambled Thursday to address a humanitarian crisis in Misurata, which has been besieged by government forces for a week.

Airstrikes destroyed government tanks on the outskirts of the city, but other tanks inside Misurata were not hit, a resident told Reuters. The tanks reentered Misurata under cover of darkness and shelled the area near the city’s hospital, where a number of wounded anti-Gaddafi fighters are being treated, residents and rebels reported.

Faced with an increasingly dire situation in Misurata, the Paris-based group Doctors Without Borders secretly delivered a boatload of medical supplies to the city Monday night, an official with the aid group said. The city has no electricity or running water, and the hospital is struggling to cope with wounded people, residents have reported.

Fighting also continued Thursday in the eastern city of Ajdabiya, which straddles highways leading north to Benghazi and east to Tobruk. Residents of the city said they, too, have no water or electricity and are coming under indiscriminate fire from loyalist forces on the outskirts.

In the town of Zintan about 100 miles southwest of Tripoli, rebels are holding out against Gaddafi forces positioned outside the town with more than 30 tanks, a Swiss journalist there told Reuters by telephone. Eight rebels have died in Zintan and about 20 have been wounded in fighting there in recent days, the journalist said.

In Paris, French Foreign Minister Alain Juppe told reporters that the Western military operations against Gaddafi’s forces could last for days or weeks, but not months.

“You can’t expect us to achieve our objective in just five days,” he said, addressing concerns about a prolonged conflict.

Bahrampour reported from Benghazi, Libya.