Loud explosions and heavy anti-aircraft gunfire were heard in the Libyan capital city of Tripoli at around 9:00 p.m. local time (1900 GMT) on Monday as the third round of Western-led airstrikes started.

Anti-aircraft artilleries were fired into the sky from the north and east parts of the city, while the anti-aircraft fire was also heard in south part of the city.

One military barrack 30 km west to Tripoli was bombed, a local source told Xinhua reporters Monday.

A navy base near the broadcasting and TV station in the capital was targeted in the military strikes, which also hit an oil pipeline in Shaab, a port city east of Tripoli.

After the explosion, Libyan government spokesman Mussa Ibrahim held an emergency press conference to strongly protest the bombing.

He said Western countries has launched three consecutive days of air strikes after Libyan armed forces announced a comprehensive cease-fire and stopped all military actions. The majority of Libya's civil airports and seaports were destroyed during the airstrikes.

Libyan state TV said many civilians were killed and wounded in the new round of attacks.

Similar explosions rocked the capital on Sunday, with coalition officials on Monday saying an administrative building of the residence compound of Libyan leader Muammar Gaddafi was destroyed by a missile.

Footage of the Libyan state TV showed that a building near the tent where Gaddafi usually receives guests was severely damaged.

"It was a barbaric bombing" and could have hit hundreds of civilians who gathered near the destroyed building in support of the Libyan leader, said Mussa, who declined to say whether Gaddafi was still inside the compound.

He said the airstrikes have caused heavy civilian casualties. At least 64 Libyans had been killed and 150 others wounded by the missiles and bombs rained upon Libya over the weekend. But the intervening forces denied targeting civilians.

Government forces of Libya pulled back 100 km from the main opposition stronghold of Benghazi on Monday after a weekend of air attacks.

The forces retreated to the strategic town of Ajdabiya, south of Benghazi, after the airstrikes destroyed much of their armor and seriously degraded the North African country's air defense systems.

Dubbing the attacks "a crusader war" against the Libyan people, Gaddafi said Sunday that the airstrikes were "terrorist means" and he vowed a "long war."

Echoing Gaddafi's warning, a top French official said that the international military action against Libya is likely to last "a while."

Henri Guaino, a top adviser to French President Nicolas Sarkozy, told RMC radio that the strikes dealt a serious blow to Libya's air defenses and stalled Gaddafi's troops.

Libyan people's patriotic sentiment has run high after Western countries launched the joint military action. Pro-Gaddafi rallies and protests against the military intervention in Libya were seen as many people and students would take to the streets after work or school.

A Xinhua correspondent said the government has already opened arms depots to the people to protect the country and any Libyan citizen who registers at the government department can get guns and bullets now.

Meanwhile, U.S. President Barack Obama on Monday said that it is U.S. policy that Gaddafi needs to go, adding that U.S. military actions will stick to the "international mandate" given by the United Nations.

"I also have stated that it is U.S. policy that Gaddafi needs to go," Obama said in the joint press conference with Chilean President Sebastian Pinera.

"We've got a wide range of tools in addition to our military efforts to support that policy," he said, referring to U.S. unilateral sanctions and U.S. push for international sanctions on the Gaddafi government.

But he stressed that the current U.S. military action is in support of an "international mandate" from the UN Security Council that specifically focuses on the humanitarian threat posed by Gaddafi, and the U.S. will stick to that mandate.

The UN Security Council Resolution 1973 adopted on Thursday authorized a no-fly zone over Libya to "protect civilians" of the country, which is different from the U.S. policy to see the toppling of Gaddafi.

"There is going to be a transition taking place in which we are one of the partners among many who are going to ensure that no-fly zone is in force and that the humanitarian protection that needs to be provided continues to be in place," said Obama.

Also on Monday, U.S. Defense Secretary Robert Gates said in an interview with Russia's Interfax news agency that the United States will soon scale down its participation in the military actions against Libya.

Speaking in Russian city of St. Petersburg, Gates also said it would be a mistake for the coalition to set for itself a goal of eliminating Gaddafi.

"It is clear to everybody that Libya will be better-off without Gaddafi. But that is a matter for the Libyans themselves to solve. And I think given the opportunity and the absence of repressions they themselves can do that and I think it would be a mistake of us to set that as a goal," he said.

(Xinhua News Agency March 21, 2011)