Libyans pray over six bodies recovered from a mass grave, allegedly of people killed by the Moamer Qadhafi regime some 20 years ago, during Friday noon prayers at the Revolution Square in the rebel stronghold city of Benghazi. Turkey has offered Qadhafi "guarantees" to leave Libya but has yet to receive a reply. - AFP Photo

TRIPOLI: Turkey has offered Moamer Qadhafi guarantees to leave Libya but has yet to receive a reply, as rebels say loyalist forces killed 20 people in a fierce assault on Misrata.

Fresh Nato-led strikes sent up plumes of smoke Friday in Tripoli, where the strongman has his residence and headquarters.

But in Brussels, US Defence Secretary Robert Gates warned the Western alliance's air war on forces loyal to Qadhafi could be in peril because of military shortcomings.

Turkish Prime Minister Recep Tayyip Erdogan said his government had offered exit “guarantees” to the embattled Libyan leader, whom rebels have been trying to oust since February following a bloody crackdown on pro-reform protests.

Qadhafi “has no other option than to leave Libya - with a guarantee to be given to him,” Erdogan said on NTV television.

“We have given him this guarantee. We have told him we will help him to be sent wherever he wants to go,” he added, without elaborating.

“Depending on the reply we will get from him, we will take up the issue with our (Nato) allies, but unfortunately we have received no reply so far.” His comments came after a day of deadly fighting near the port city of Misrata, the rebels' most significant enclave in western Libya, some 200 kilometers from Tripoli.

Qadhafi's forces had bombarded the Dafnia area on Misrata's outskirts with Grad rockets, heavy artillery and tank shells, a rebel said.

“Twenty people, both civilians and rebels, were killed and more than 80 wounded,” in the sector, 35 kilometers from Misrata city centre, he added.

But they had beaten back an attack by loyalist troops, leaving “dead and wounded among the Qadhafi forces,” he said.

In the Libyan capital Tripoli, two loud blasts were heard at about 3:00 pm (1300 GMT), coming from the eastern suburbs of Tajura and Ain Zara, residents told AFP.

Three powerful explosions shook the city centre at around midnight. Other more distant blasts followed.

Tripoli has over the past two days been subjected to the most intense Nato air raids since the international military campaign was launched on March 19 under a UN mandate to protect Libyan civilians.

In Paris, Libyan leader Moamer Qadhafi's daughter Aisha filed a second war crimes complaint against Nato and France over air strikes that killed family members, including three infants, her lawyer said.

In Moscow, Russian President Dmitry Medvedev's special envoy Mikhail Margelov said he would be visiting Tripoli to try to find a solution to the conflict, having met the opposition in their Benghazi stronghold.

Thursday saw a surge of support for the rebels battling to oust Qadhafi at a meeting in Abu Dhabi of the International Contact Group on Libya.

Key powers agreed to unlock a billion dollars for their coffers, and the United States joined Australia and Spain in recognising the rebels National Transitional Council (NTC) as Libya's legitimate representative.

Gates, the Pentagon chief, expressed concern Friday with half of the countries in the 28-member Nato alliance not participating in the Libya campaign, many simply did not have the wherewithal.

“Frankly, many of those allies sitting on the sidelines do so not because they do not want to participate, but simply because they cannot,” Gates said.

“The military capabilities simply aren't there.” Norway, which has contributed six F-16 fighters, said however that it would first reduce its participation before pulling out altogether on August 1.

And Dutch Prime Minister Mark Rutte said that while his country supported a three-month extension of the Nato air campaign, its six F-16s would not fly bombing missions.

US Senator Carl Levin, head of the Senate Armed Services Committee, said later that Qadhafi's forces had been “severely degraded” and the Nato operation was “going well”, following a briefing from Pentagon officials.

Qadhafi sent a letter to the US Congress praising its criticism of President Barack Obama over Libya, a Washington source said.

“We are confident that history will see the wisdom of your country in debating these issues,” said the letter seen by AFP, signed by Qadhafi as “Commander of the Great Revolution.” Congressional sources said they could not confirm the letter's authenticity.

A UN top official meanwhile objected to a colleague's sceptical reaction to reports of mass rape in Libya.

On Thursday, UN human rights investigator Cherif Bassiouni expressed doubts over claims by the chief International Criminal Court prosecutor Luis Moreno-Ocampo of evidence that Qadhafi had ordered mass rapes.

Margot Wallstroem, the UN special representative of the secretary-general on sexual violence in conflict objected to Bassiouni's suggestion that the reports might be down to “massive hysteria.” I think we should avoid such language,” said Wallstroem.

“What does it stand for? Does it mean that media has reported repeatedly? Does this constitute hysteria?”