|Eight warships are said to have been hit by NATO air strikes on Thursday night [Reuters]
The NATO military alliance says it has sunk eight warships belonging to Libyan leader Muammar Gaddafi's forces.
The ships were targeted in co-ordinated overnight attacks on the ports of Tripoli, Al Khums and Sirte, the alliance announced on Friday.
The deputy commander of the NATO mission in Libya said the air strikes were needed to protect civilians and NATO forces at sea.
Shelling was also heard in the Ghabat al-Qasr neighbourhood of the capital, Tripoli, in the early hours of Friday.
NATO, acting under a UN mandate, has been carrying out air strikes on Libya since Gaddafi used force to put down a revolt inspired by uprisings elsewhere in the Arab world.
In some of the latest strikes, NATO hit Gaddafi's forces around 15km east of the opposition-held town of Zintan in the Western Mountains region. The town and the port city of Misurata have seen some of the heaviest fighting in recent weeks.
Al Jazeera has also confirmed there is heavy fighting on the Tunisia-Libya border. Casualty numbers however are not yet known.
Anders Fogh Rasmussen, the NATO secretary-general, said the ongoing strikes have helped to weaken Gaddafi's hold on power in Libya and will eventually topple him.
"We have significantly degraded Gaddafi's war machine. And now we see results, the opposition has gained ground," he told a news conference in the Slovak capital, Bratislava, on Thursday.
"I am confident that a combination of strong military pressure and increased political pressure and support for the opposition will eventually lead to the collapse of the regime."
He also stressed that the NATO mission was restricted to enforcing a UN-mandated no-fly zone and that there were no plans for alliance troops to set foot on Libyan soil.
Libyan officials, however, have described the NATO intervention as an act of colonial aggression aimed at grabbing Libya's oil.
'Decades of provocation'
Rasmussen’s comments were echoed by US president Barack Obama.
"Time is working against Gaddafi. He does not have control over his country. The opposition has organised a legitimate and credible interim council," Obama said in Washington on Thursday.
"When Gaddafi inevitably leaves or is forced from power, decades of provocation will come to an end and the transition to a democratic Libya can proceed," he said, defending his decision to take military action against the Libyan leader's government.
But Libyan government spokesman Mussa Ibrahim criticised the US president's remarks, saying "Obama is still delusional".
"It is not Obama who decides whether Muammar Gaddafi leaves Libya or not, it is the Libyan people who decide their future," he told reporters.
Ibrahim also said the government is offering to withdraw their fighters from cities if opposition fighters do the same, as part of a peace deal. He said that a Libyan envoy made the offer while meeting Russian leaders in Moscow on Tuesday.
The spokesman added that the offer was the furthest the government had gone since fighting broke out against rebels seeking to overthrow the Gaddafi-led government.
Ibrahim said as part of the deal, NATO would also have to halt its strikes of Libyan targets.
There was no immediate comment from opposition leaders based in the eastern city of Benghazi.
Opposition forces control eastern Libya and pockets in the west, but the conflict has effectively reached a stalemate in military terms, with opposition attempts to advance on Tripoli, Gaddafi's stronghold, stalled.
However, the conflict has claimed the lives of thousands, according to rights groups. Numerous media workers have also died, with a South African photographer being the latest casualty.
A statement on a social networking site by the family of Anton Hammerl, a freelance photographer who had been missing in Libya for more than a month, said they learned he had been killed on April 5 by pro-Gaddafi forces.
In a statement, the family said Hammerl had been killed in an "extremely remote location" and injured to a degree that "he could not have survived without medical attention".