Smoke billows following an air raid on the area of Tajura, 30 km east of Libya's capital on May 24 [AFP]

Libya's capital, Tripoli, has been rocked by a series of NATO air strikes for the fifth night in a row, Libyan state television reported.

A number of explosions were heard throughout the night into Saturday, and at least one of the blasts was said to be near a compound used by Muammar Gaddafi, the Libyan leader.

Columns of smoke were seen rising over the skyline of the city and loud booms could be heard.

State television said the overnight NATO raids also caused "human and material" damage near Mizda, to the south.

Misurata, Libya's third largest city now controlled by opposition forces and the scene of some of the fiercest battles in the conflict, was hit by a second day of heavy fighting on its western outskirts on Friday.

Doctors at the local hospital said five opposition fighters were killed and more than a dozen others wounded.

Forfeiting legitimacy

The series of overnight attacks and clashes came just hours after Russian president Dmitry Medvedev agreed to mediate Gaddafi's exit, saying the Libyan leader had "forfeited legitimacy" to rule.

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Medvedev told reporters  from the G8 summit in France on Friday that Gaddafi "should leave".

"If Gaddafi makes this decision, which will be beneficial for the country and the people of Libya, then it will be possible to discuss the form of his departure, what country may accept him and on what terms, and what he may keep and what he must lose," Medvedev told reporters.

Previous attempts at mediation by the African Union, Turkey and the United Nations have collapsed upon Gaddafi's refusal to leave and the opposition's refusal to accept anything less.

Russia, which has previously criticised NATO's involvement in Libya, is possibly in a position to end the conflict, although some analysts are sceptical of its level of influence, given Gaddafi's resistance to other mediation attempts and insistence on maintaining power throughout the conflict.

More local powers were unconvinced by any real potential for change through Russia's mediation.

"Knowing his state of mind, I don't think he is going to step down," Arab League secretary-general Amr Moussa said.

Libyan opposition spokesman and vice-chairman of the opposition's National Transitional Council, Abdel-Hafidh Ghoga, said Russia's offer should have come sooner.

"It's too late, and it's not a big deal," he said.

Analysts have also suggested that Russia's new-found willingness to mediate in Libya could be a part of its hope to gain some level of influence in the region in the post-uprising Arab world.

Medvedev could also be eyeing Libya's oil and gas markets, analysts have said, and preparing for the prospect that the lucrative Libyan market will fall into full opposition control.

Source: Al Jazeera and agencies