British warplanes struck a large bunker in Muammar Gaddafi's hometown of Sirte, his largest remaining stronghold, as Nato focused on loyalist forces trying to hold back advancing rebels.

The air strikes came a day after fierce clashes erupted in the Libyan capital, which remained tense as rebels hunted for the elusive leader and his allies, detaining suspected loyalists and raising concerns about human rights violations.

Rebels were searching for the remnants of pro-Gaddafi forces in Tripoli's Abu Salim neighbourhood, which saw very heavy fighting the day before.

The rebels had detained seven men and one woman and loaded them into a pickup truck in a rural area between Abu Salim and the airport, saying Gaddafi forces might be trying to blend in with civilians.

"Things are still not stable and we are arresting anybody we find suspicious and taking them to the military council," said field commander Fathi Shneibi.

Meanwhile, at a clinic attached to an Abu Salim fire station, injured men believed to be Gaddafi supporters or fighters were left moaning and calling for water.

Curious neighbourhood men climbed the stairs to look at them, but none offered help.

One of the wounded said he was from Niger and denied any links to Gaddafi. Asked why he was in Libya, he said, "I really don't know."

Signs also emerged that the situation can turn far worse.

Dozens of decomposing bodies were piled up in an abandoned Abu Salim hospital, a grim testament to the chaos in the capital.

It was not clear when the men had been killed. The floors were covered with shattered glass and bloodstains, and medical equipment was strewn about.

One room had 21 bodies lying on stretchers, with 20 more in a courtyard next to the car park - all of them darker skinned than most Libyans.

Gaddafi had recruited fighters from sub-Saharan Africa, but many others from the region are in Libya as migrant workers.

It was not clear who had killed the men, but since the uprising began the rebels often suspect sub-Saharan Africans of being mercenaries.

A spokesman for the International Committee of the Red Cross, Steven Anderson, said the neutral aid group was concerned about the treatment of detainees on both sides in Tripoli.

The Geneva-based ICRC has been able to visit some prisoners on both sides, said Anderson, but "there are hundreds more probably."

Tripoli, meanwhile, enjoyed the quietest day yet since the rebel takeover, though pro-Gaddafi forces were shelling the airport and sporadic shooting was reported elsewhere.

At the first Friday prayers since Tripoli fell to the rebels, hundreds of people crowded a mosque in central Tripoli, listening as the imam praised the rebels for taking up arms against Gaddafi.

He said they had "liberated the land inch by inch, house by house, alley by alley," using a famous phrase from a Gaddafi speech against the uprising.

Hearing the phrase, worshippers laughed or shouted "Allahu Akbar!"

Afterward, the worshippers marched out chanting in support of revolution. "Hold your head high, you are a free Libyan," some shouted.

There had been a plan to hold prayers at the Martyr Square, which was called Green Square under Gaddafi's regime, but it was littered with bullet casings and rubbish so worshippers decided to hold the service at a nearby mosque.

Mahmoud Shammam, a spokesman for the rebel council, told reporters in Tripoli that the rebel government had begun shifting from Benghazi to Tripoli, taking over official buildings and setting up a security committee.

He also said some people from Gaddafi's regime would be included in the new government.

"The only people we are going to exclude are the people who killed others and stole money," Shammam said in Tripoli.

The military alliance said Nato warplanes targeted 29 vehicles mounted with weapons near Sirte, a city of 150,000 about 250 miles east of Tripoli.

Rebels are trying to advance toward Sirte but expect fierce resistance from tribesman and townspeople loyal to Gaddafi.

The rebel leadership, trying to avoid the bloodshed that occurred in the battle for Tripoli, has also been trying to secure Sirte's surrender, but the two main tribes have rejected negotiation efforts.

Gaddafi denied his people basic rights, cracked down harshly on any hint of dissent and squandered the country's vast oil and gas wealth.

But tribal loyalties are strong in the desert nation of six million. Gaddafi also placed supporters in key posts and built up militias and armed "revolutionary committees" to be the final line of support for him and his powerful sons if regular military forces defected.

Gaddafi has tried to rally his followers from hiding, calling on them in an audio appeal as recently as Thursday to fight and kill the rebels.

The two main tribes in Sirte, the Gadhadhfa and the Urfali, remain loyal to the Libyan leader.

Mohammed al-Rajali, a spokesman for rebel fighters in the east, said the rebels were trying to reach out to smaller tribes in Sirte but no progress had been made.

But the latest Nato air strikes on loyalist vehicles defending Sirte appeared aimed at paving the way for the rebel advance if a negotiated settlement proves impossible.

In London, British Defence Secretary Liam Fox said some elements of the Gaddafi regime were in Sirte "where they are still continuing to wage war on the people of Libya." He said Nato would continue to strike at pro-Gaddafi forces.

"The regime needs to recognise that the game is up," Fox said.

Major General Nick Pope, a British military spokesman, said RAF jets also hit a large headquarters bunker in Sirte with a salvo of air-to-surface missiles.

Nato also bombed surface-to-air missile facilities near the Tunisian border, a statement said.

The Tripoli airport was under rebel control but faced regular shelling from pro-Gaddafi forces to the east. At least three planes were burned in heavy shelling overnight, although the airport otherwise appeared largely intact, with a dozen other passenger planes on the tarmac.