Sole command of military operations in Libya was passed to NATO early Thursday from United States.

After overcoming internal division over whether to give NATO command of the campaign in Libya, the transition of authority was completed early Thursday, NATO Secretary General Fogh Rasmussen said in a statement.

"In line with the mandate of the United Nations Security Council Resolution 1973, NATO's focus is on protecting civilians and civilian-populated areas against the threat of attack," he said.

With a 28-member coalition and code-named "Operation Unified Protector," the NATO mission is under the command of Canadian Gen. Charles Bouchard, who will give orders from Naples, Italy.

Stepping aside, the United States said it will reduce its involvement in the mission and keep to a supporting role.

Testifying before the House and Senate Armed Services Committees Thursday, U.S. Defense Secretary Robert Gates said American participation will be limited and would not involve an active role in air strikes as time goes on.

He also said the Obama administration has no further military planning beyond those already authorized.

While countries like the United States, Great Britain, France Denmark, Canada and Belgium conducted air raids in Libya, other NATO members either insist on staying away from the military operation or refused to let their fighter jets participate the air strikes.

Following Oatar, the United Arab Emirates has also sent fighter planes as part of the coalition force to police the no-fly zone over Libya's sky, a French armed forces spokesman confirmed Thursday.

Besides declaring NATO's sole command status in the operation, the NATO chief also said he opposed arming the Libyan rebels.

"As far as NATO is concerned, we will fully implement the U.N. Security Council resolution which requests the enforcement of the arms embargo, and the purpose of the arms embargo is to stop the flow of weapons into Libya," Rasmussen said.

Some western powers, including the U.S. and the UK are mulling the possibility of supplying weapons to the rebels. The idea was rejected by Italy, Russia, Norway, Belgium and Denmark. The French defense minister said Thursday supplying arms to the rebels was not "on the agenda."

The British defense ministry said Thursday its warplanes have bombed Libya's tanks, armored vehicles and a surface-to-air missile site around Misrata.

The latest rounds of air strikes came as rebel fighters demanded additional air strikes after their reluctant pulling out from Libya's key oil port of Ras Lanouf.

The poorly equipped rebels, however, still seem no match for government troops. Their setbacks are hardening the U.S. view that they are probably incapable of prevailing without decisive Western intervention, a senior U.S. intelligence official told The Associated Press.

Meanwhile, Libyan leader Muammar Gaddafi and his sons are still showing no signs of departing the country, saying they would stay to the very end, according to Libya's government spokesman Mussa Ibrahim.

Also on Thursday, British Foreign Secretary William Hague confirmed in London that Libyan Foreign Minister Mussa Kussa is currently in UK "under his own free will".

Hague said the former top Libyan intelligence official said on his arrival that he was resigning his job, adding that he was now at a "secure place" to discuss "his options and our options."

Though still not confirming the departure of Kussa, Ibrahim told the press "we are not waiting for individuals to lead the struggle."

Kussa is privy to all the inner workings of the Libyan government. His departure could open the door for some hard intelligence, though Britain refused to offer him immunity from prosecution.

Koussa is not the first high-ranking member of the Libyan government to quit -- the justice and interior ministers resigned early in the conflict and joined the rebellion based in the east.