South African president Jacob Zuma flies into Tripoli

South African President Jacob Zuma flew into Tripoli today to try to broker a peace deal with Muammar Gaddafi (GETTY)

South African President Jacob Zuma flew into Tripoli on Monday to try to broker a peace deal with Muammar Gaddafi, just hours after Nato's secretary-general said the Libyan leader's "reign of terror" was coming to an end.

In Rome, eight Libyan army officers including five generals appeared at an Italian government-arranged news conference, saying they were part of a group of as many as 120 military officials and soldiers who defected from Gaddafi in recent days.

Libyan UN ambassador Abdurrahman Shalgam, who has also defected from Gaddafi, said all 120 of the military personnel were outside Libya now but he did not say where they were.

On arrival in Tripoli Zuma was met by a host of dignitaries, not including Gaddafi himself, who has not been seen since May 11 when he was shown by Libyan state television meeting what it said were tribal leaders.

Zuma's walk down the red carpet at Tripoli airport was accompanied by a band and children chanting "We want Gaddafi!" in English while waving Libyan flags and pictures of the leader.

Zuma's visit is his second since the conflict began in February. His previous trip made little progress because Gaddafi has refused to relinquish power, while rebel leaders say that is a precondition for any truce.

Nato warplanes have been raising the pace of their air strikes on Tripoli, with Gaddafi's Bab al-Aziziyah compound in the centre of the city being hit repeatedly.

Journalists escorted into Bab Al-Aziziyah after Zuma's arrival found a group of around 160 African visitors to Libya chanting pro-Gaddafi slogans and waving flags of nations including Chad, Niger and Ghana, in an apparent show of pan-African unity.

Britain said on Sunday it was to add "bunker-busting" bombs to the arsenal its warplanes are using over Libya, a weapon it said would send a message to Gaddafi that it was time to quit.

"Our operation in Libya is achieving its objectives ... We have seriously degraded Gaddafi's ability to kill his own people," Nato Secretary-General Anders Fogh Rasmussen told a Nato forum in Varna, Bulgaria.

"Gaddafi's reign of terror is coming to an end. He is increasingly isolated at home and abroad. Even those closest to him are departing, defecting or deserting."

Gaddafi denies attacking civilians, saying his forces were obliged to act to contain armed criminal gangs and al-Qa'ida militants. He says the Nato intervention is an act of colonial aggression aimed at grabbing Libya's plentiful oil reserves.

Britain and other Nato powers are ratcheting up the military intervention to try to break a deadlock that has seen Gaddafi hold on to power despite a rebel uprising against his four-decade rule and weeks of air strikes.

US Admiral Samuel Locklear, commander of the Joint Operations Command at Naples, declined to comment on whether Nato would put forces on the ground but suggested a small force may be needed to help the rebels once Gaddafi's rule collapses.

He told the Varna forum: "I would anticipate that there might be a need at some point to unfold a small force ... a small number of people there to help them in some way."

Britain said the Enhanced Paveway III bombs, each weighing nearly a tonne and capable of penetrating the roof or wall of a reinforced building, had arrived at the Italian air base from where British warplanes fly missions over Libya.

"We are not trying to physically target individuals in Gaddafi's inner circle on whom he relies, but we are certainly sending them increasingly loud messages," British Defence Secretary Liam Fox said on Sunday in a statement.

The military alliance says it is acting under a mandate from the United Nations to protect civilians from attack by security forces trying to put down the rebellion against Gaddafi.

But the more aggressive tactics risk causing divisions within the fragile alliance backing the intervention, and could also lead to Nato being dragged closer towards putting its troops on Libyan soil, something it is anxious to avoid.

Gaddafi's foreign minister held talks in Tunisia on Saturday with Lord David Trefgarne, a former British government minister, according to a former British ambassador to Libya who took part in the discussions.

The ex-ambassador refused to disclose what they talked about and Britain's government said neither it not any intermediaries were talking to officials loyal to Gaddafi.

Further deepening their involvement, Britain and France have said they will deploy attack helicopters over Libya to better pick out pro-Gaddafi forces. Helicopters are more vulnerable to attack from the ground than high-flying warplanes.

On Sunday Al Jazeera television station broadcast video footage of what it said were foreign forces, possibly British, on the ground near the rebel-held city of Misrata.

There were a number of armed men, some wearing sunglasses and keffiyahs, or traditional Arab headscarves, who moved off when they realised they were being watched, the footage showed.

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.

Helped by Nato air support, the rebels have been able to repel attacks by pro-Gaddafi forces but in many places they are still under bombardment and cut off from supplies.

Libyan state television reported that Nato air strikes killed 13 people in Zlitan on Monday, the next town westwards on the coast road towards Tripoli from Misrata.

The state news agency Jana also reported that Nato air strikes hit the Tiji area, near the Western Mountain town of Nalut, overnight, causing "human and material losses".