New questions have emerged over how long Gaddafi can hold on.

Tripoli - Muammar Gaddafi is emphatic he will not leave Libya, South African President Jacob Zuma said on Tuesday after talks with the Libyan leader that left prospects for a negotiated end to the conflict looking dim.

But new questions emerged over how long Gaddafi could hold on after a senior U.N. aid official said shortages of food and medicine in areas of Libya controlled by Gaddafi amounted to a “time bomb”.

Within hours of Zuma's departure from Tripoli late on Monday, Libyan television reported that NATO aircraft had resumed attacks, striking what it called civilian and military sites in Tripoli and Tajoura, just east of the capital.

Zuma was in Tripoli to try to revive an African “roadmap” for ending the conflict, which started in February with an uprising against Gaddafi and has since turned into a war with thousands of people killed.

The talks produced no breakthrough, with Gaddafi's refusal to quit - a condition the rebels and NATO have set as a pre-condition for any ceasefire - still the sticking point.

“Col. Gaddafi called for an end to the bombings to enable a Libyan dialogue,” Zuma's office said in a statement. “He emphasised that he was not prepared to leave his country, despite the difficulties.”

Zuma also said Gaddafi's personal safety “is a concern” - a reference to NATO strikes which have repeatedly hit the Libyan leader's Bab al-Aziziyah compound and other locations used by the Libyan leader and his family.

Now in its fourth month, Libya's conflict is deadlocked on the ground, with anti-Gaddafi rebels unable to break out of their strongholds and advance towards Tripoli, where Gaddafi appears to be firmly entrenched.

Rebels control the east of Libya around the city of Benghazi, Libya's third-biggest city Misrata, and a mountain range stretching from the town of Zintan, 150 km (95 miles) south of Tripoli, towards the border with Tunisia.

Speaking in the main rebel stronghold of Benghazi where he was opening a consulate, Italian Foreign Minister Franco Frattini said he had pledged an aid package for the rebels worth hundreds of millions of euros.

“I think the Gaddafi regime is over and I firmly believe that it is over for a simple reason: we are talking about a person whose closest friends are defecting. He lost his legitimacy in Libya,” Frattini said.

TIME BOMB

Western powers have said they expect Gaddafi will be forced out by a process of attrition as air strikes, defections from his entourage and shortages take their toll.

Panos Moumtzis, the U.N. humanitarian coordinator for Libya, told Reuters in Tripoli that some food stocks in areas under Gaddafi's control were likely to last only weeks.

“I don't think there's any famine, malnutrition. But the longer the conflict lasts the more the food stocks supplies are going to be depleted, and it's a matter of weeks before the country reaches a critical situation,” Moumtzis said.

“The food and the medical supplies is a little bit like a time bomb. At the moment it's under control and it's ok. But if this goes on for quite some time, this will become a major issue,” he said.

Gaddafi says his forces are fighting armed criminal gangs and al Qaeda militants, and has described the NATO intervention as an act of colonial aggression aimed at grabbing Libya's plentiful oil reserves.

Libyan television showed Gaddafi welcoming Zuma, his first public appearance since May 11. Speculation had been swirling that Gaddafi was injured in a NATO strike or had fled Tripoli.

MISRATA FIGHTING

In London, British-based opposition activist Noman Benotman said Libyan forces in Tripoli had arrested two prominent Islamist opponents of Gaddafi, Sami al-Saadi, the spiritual leader of the now defunct Libyan Islamic Fighting Group (LIFG), and the group's former deputy leader Khalid al-Sharif.

There was no immediate confirmation of the report. The LIFG waged an insurgency against the state in Libya's east in the 1990s and made several failed attempts to assassinate Gaddafi.

Saadi and Sharif were among several hundred former LIFG men freed from long prison terms in the last three years under reforms to foster reconciliation with opposition groups.

A Reuters photographer in Misrata said there was heavy fighting in the suburb of Dafniyah, in the west of the city, where the front line is now located after rebel fighters drove pro-Gaddafi forces out of the city.

Speaking from a field hospital near the front line, she quoted medical workers as saying one person had been killed and 29 people had been injured so far on Tuesday.

“Gaddafi's forces are firing Grad rockets,” she said. “The rebels tried to advance, and Gaddafi's forces pushed back.”

Rebel fighters, out of their familiar urban battleground, were being outgunned, one of their spokesmen said.

“The situation is getting more difficult for the revolutionaries because fighting is going on in open places. They do not have the same heavy weapons as the (pro-Gaddafi) brigades,” the spokesman, Abdelsalam, said from Misrata.

There were reports too of clashes between rebels and forces loyal to Gaddafi in the Western mountains.

NATO PERFORMANCE “WEAK”

A rebel spokesman in the town of Zintan told Reuters by telephone: “Fighting took place last night in (the village of) Rayayna, east of Zintan ... It continued until the early hours of this morning. Both sides used mortars.”

“The revolutionaries do not want to intensify attacks in the area for fear of harming civilians still living there,” said the spokesman, called Abdulrahman.

He urged NATO to take a more active role by targeting pro-Gaddafi forces from the air.

Using a makeshift system of citizens' band radios and Skype, local rebels have been passing on government positions to NATO via the rebel headquarters in Benghazi, eastern Libya.

“Nato's performance is still very weak. Its operations are very slow despite the fact that the local (rebel) military council has provided it with all necessary information about the brigades' positions,” said Abdulrahman.

In an apparent effort to generate an atmosphere of business as usual, official Libyan media said tourism officials met on Tuesday to examine preparations for the summer season, discussing topics such as summer camps and public parks. - Reuters