TRIPOLI (AFP) – NATO warplanes hit eight vessels of Moamer Kadhafi's navy, the alliance said as US President Barack Obama answered constitutional questions regarding the length of the Libyan conflict.

Also Friday, the United States said it delivered 120,000 Halal meals to Libyan rebels as part of US plans to provide $25 million in non-lethal aid to forces fighting Kadhafi's regime.

Meanwhile, authorities in Tripoli slammed Obama as "delusional" for earlier suggesting that the veteran Libyan leader's departure is inevitable.

They also strongly denied reports that Kadhafi's wife and daughter had fled to Tunisia and that Oil Minister Shukri Ghanem had defected.

NATO said it carried out "precision air strikes" in the ports of Tripoli, Al-Khums and Sirte, striking eight vessels.

"Given the escalating use of naval assets, NATO had no choice but to take decisive action to protect the civilian population of Libya and NATO forces at sea," said Rear Admiral Russell Harding, deputy head of the NATO-led air war.

Explosions were heard in the Libyan capital early Friday, hours after the air strikes targeted the city's port, with a ship still ablaze from the raid.

Harding insisted that all of the targets hit were military but government spokesman Mussa Ibrahim accused NATO of seeking to scare international shipping firms into steering clear of government-held ports.

"Whatever the ship that has been hit, it is clearly a message sent by NATO to the international maritime companies not to send any more vessels to Libya," Ibrahim told reporters.

British aircraft targeted Al-Khums, the nearest naval base under the control of Kadhafi forces to the rebel-held city of Misrata, British defence staff spokesman Major General John Lorimer said.

"As well as hitting two corvettes in the harbour, the Royal Air Force Tornados successfully targeted a facility in the dockyard constructing fast inflatable boats, which Libyan forces have used several times in their efforts to mine Misrata and attack vessels in the area," Lorimer said.

"The destruction last night of the facility and a significant stockpile of the boats will reduce the regime's ability to sustain such tactics," he added.

NATO has increased the pressure on Kadhafi by hitting several command and control centres in Tripoli in recent days.

"This has limited Kadhafi's ability to give orders to his forces. It has also constrained his freedom of movement; effectively he's gone into hiding," NATO's Wing Commander Mike Bracken said in Brussels.

In Tripoli, the government spokesman described as "delusional" Obama's prediction in a speech Thursday that the veteran Libyan leader's departure is inevitable.

"Obama is still delusional -- he believes the lies that his own government and own media spread around the world," Ibrahim said.

"It's not Obama who decides whether Moamer Kadhafi leaves Libya or not. It's the Libyan people who decide their future."

The Pentagon said Friday its first shipment of the ready-to-eat meals arrived in the rebel stronghold of Benghazi on May 10 after the United States announced plans to provide non-lethal assistance to the rebels.

Other assistance -- including medical supplies, tents, uniforms, sandbags, flak jackets -- will be delivered in the coming weeks, a spokesman said.

Obama sent a letter to Congress, asking for political support of US action in the NATO assault, as he hit a technical 60-day deadline to get official congressional approval for the use of his war powers.

The White House maintains that its support role to allies does not merit a formal declaration of war as is required by the US Constitution.

It also said the action falls short of the kind of campaign governed by the 1973 War Powers Act that requires any military action longer than 60 days to be authorized by Congress.

But in a letter, Obama said it would be helpful instead if lawmakers backed a binding resolution to underline US support.

Meanwhile, the family of South African photographer Anton Hammerl, missing for six weeks, said he had been fatally shot by Kadhafi's forces on the front line between rebel-held eastern Libya and the mainly government-held west.

"Anton was shot by Kadhafi's forces in an extremely remote location in the Libyan desert," said a statement posted on Facebook.

South African authorities only learned of Hammerl's death after the release on Wednesday of four other journalists who were with him when he was shot, South African Foreign Minister Maite Nkoana-Mashabane said.

"The journalists knew that he had been killed but decided for their own survival not to say anything in consular contacts and telephone conversations with their families."

Also Friday, rebels said they will soon deport four Frenchmen they have been holding inBenghazi since May 11 after arresting them on suspicion of spying.

A fifth Frenchman, ex-paratrooper Pierre Marziali, had been "accidently" shot dead by the rebels in a murky incident at a checkpoint.

Marziali was the founder of private security firm Secopex which had opened an office in Benghazi and his four companions were also working for the firm.

Also, African Union leaders will gather for an extraordinary summit in Addis Ababa next week to discuss the Libyan conflict, the organisation announced.

Last month, pan-African body proposed a truce but it was rejected by rebels, who insisted on Kadhafi's departure.