NATO air strikes may force Libya to halt fighting by its army in the besieged port of Misrata and let local tribes take over the battle, the government said, in what could amount to an important shift in the battlefield city.

Hours after the announcement of a shift in tactics in Misrata by forces of leader Muammar Gaddafi, NATO bombs struck what appeared to be a bunker near his compound in central Tripoli. The government said the target was a car park and three people were killed.

"The situation in Misrata will be eased, will be dealt with by the tribes around Misrata and the rest of Misrata’s people and not by the Libyan army," Deputy Foreign Minister Khaled Kaim told reporters in Tripoli.

"You will see how they will be swift and quick and fast and the Libyan army will be out of this situation in Misrata, because the Libyan people around Misrata cannot sustain it like this," he said.

"The tactic of the Libyan army is to have a surgical solution, but it doesn’t work, with the air strikes it doesn’t work."

Misrata, the last large city held by rebels in the west of the country, has been under siege for nearly two months. Hundreds of people have died in shelling and fighting, petrol is scarce and thousands of migrant workers are trapped there.

Western countries have vowed not to stop bombing Libya until Gaddafi leaves power, but their air war now in its second month has so far failed to tip the balance.

There have been signs of rebel success in recent days in Misrata. Insurgents seized control of a downtown office building that had been a base for Gaddafi’s snipers and other troops after a furious two-week battle.

Shattered masonry, wrecked tanks and the incinerated corpse of a government soldier lay near the former insurance offices on Friday.

"They shot anything that moved," one fighter said of the Gaddafi men driven out.

Bomb hits Tripoli

NATO jets hit a target near Gaddafi’s compound in central Tripoli early on Saturday. Government spokesman Mussa Ibrahim said three people were killed by the "very powerful explosion" in a car park near Gaddafi’s Bab al-Aziziyah compound.

Reuters reporters said the area was surrounded by a wall and guarded by watchtowers and soldiers. They saw two large holes in the ground where the bombs had torn through soil and reinforced concrete, to pierce what appeared to be an underground bunker.

Smoke was rising from one of the craters and ammunition crates lay nearby. Ibrahim said the area was disused and the ammunition boxes were empty.

On Friday, US Senator John McCain became the highest-profile Western politician to visit Libya’s rebel-held areas. He expressed impatience with Washington’s cautious use of military power and said the United States should deploy ground attack aircraft and recognize the rebel government.

The visit by McCain, the senior Republican politician who ran against Barack Obama for the presidency in 2008, raises the political stakes over a war that the top US military officer acknowledged was headed toward stalemate.

Since the initial days of the strikes, Obama has ordered his troops to take on a backseat military role, reluctant to become embroiled in a third war in a Muslim country and leaving ground strikes to Washington’s NATO allies.

This week, US forces said they would send drones to carry out ground strikes. In the rebels’ eastern stronghold of Benghazi, McCain said Washington should use low-flying attack planes, among the most feared tactical weapons in its arsenal.

"It is still incredibly puzzling to me that the two most accurate close air support weapons systems, the A-10 and the AC-130, have been taken out of the fight," he said on Friday.

Admiral Mike Mullen, chairman of the US military’s joint chiefs of staff, told US troops in Baghdad that Western-led air strikes had degraded between 30 and 40 percent of Gaddafi’s ground forces. Referring to the conflict, he said: "It’s certainly moving toward a stalemate.

McCain said Washington should recognize the rebels’ Transitional National Council as the official government of Libya, a step already taken by France.

"They have earned this right and Gaddafi has forfeited it by waging war on his own people," he said.

White House spokesman Jay Carney, asked about McCain’s appeal, replied: "We think it’s for the people of Libya to decide who the head of their country is, not for the United States to do that."

Sources close to French President Nicolas Sarkozy said he planned to visit Benghazi, probably in the first two weeks of May, and that he wanted British Prime Minister David Cameron to accompany him.