Libya: South Africa's Jacob Zuma in peace mission
South African President Jacob Zuma is in Libya's capital, Tripoli, for talks with Col Muammar Gaddafi to seek a diplomatic solution to the conflict.
A spokesman said Mr Zuma's aim was a ceasefire and denied he would discuss exit strategies with the Libyan leader.
Government officials insist Col Gaddafi has no intention of stepping down or leaving Libya, as the rebels demand.
Meanwhile, another eight senior Libyan army officers have defected to the rebels.
The eight, including five generals, appeared at a news conference in Rome organised by the Italian government.
The rebels say a total of 120 soldiers have defected in recent days.
Since the start of the uprising in February dozens of army officers, government ministers, and diplomats have abandoned Col Gaddafi.Humanitarian priority
As Mr Zuma arrived at Tripoli's airport on Monday, children waved Libyan flags chanting "We want Gaddafi", the Reuters news agency reports.
One of Col Gaddafi's advisers admits the South African president's visit may be their last chance of a diplomatic way out, but says there's no possibility of the man they call the Brother Leader stepping aside - as both Nato and the rebels are demanding.
There is support for the alliance, though, on the streets of Tripoli, even as life gets tougher. Petrol shortages are now so severe that people report queuing for up to five days.
No-one likes being bombed, said one resident and anti-Gaddafi campaigner, but we need Nato to get rid of him.
But his opponents are still too scared to protest openly in Tripoli.
Col Gaddafi - who was last seen on state television meeting tribal leaders on 11 May - was not among the dignitaries who greeted him.
The president was later taken to Col Gaddafi's house in the Gargour area of Tripoli, where Libyan officials said his son Saif al-Arab was killed in a Nato strike in late April.
Mr Zuma's office said the main objective of his visit was to discuss with Col Gaddafi an immediate ceasefire, the delivery of humanitarian aid and the implementation of reforms needed to end the crisis.
It also rejected as "misleading" reports that their talks would focus on agreeing an exit strategy for Col Gaddafi.
Nato imposed a no-fly zone in Libya and began bombing Col Gaddafi's forces in March as they threatened to overrun rebel-held parts of the country, a month after nationwide anti-government protests began.
South Africa voted for the UN Security Council resolution authorising the use of force to protect civilians in Libya despite the AU's concerns. Since then, Mr Zuma has joined other African leaders in accusing Nato of overstepping its mandate and calling for an end to the bombardment.
The BBC's Andrew North in Tripoli says some hope Mr Zuma's personal relationship with Col Gaddafi will make a deal possible.
But the prospects for this peacemaking bid look just as thin as last time, our correspondent says.
Libya - Key diplomatic initiatives
22 Feb - Arab League suspends Libya
26 Feb - UN Security Council resolution 1970 imposes sanctions on Col Gaddafi and his family, and refers crackdown to International Criminal Court
10 Mar - France recognises rebel Transitional National Council as sole representative of Libyans
17 Mar - UN Security Council resolution 1973 authorises no-fly zone over Libya and use of "all necessary measures" to protect civilians
29 Mar - Governments and organisations agree at meeting in London to set up Libya Contact Group to co-ordinate efforts in post-Gaddafi Libya
10 Apr - Col Gaddafi accepts African Union's "roadmap" for ending conflict after visit by South African President Jacob Zuma; rebels reject plan as it does not require Col Gaddafi to step down
5 May - Ministers from Contact Group agree in Rome to set up non-military fund to help rebels
16 May - ICC's prosecutor seeks arrest of Col Gaddafi, his son Saif al-Islam, and intelligence chief Abdullah al-Sanussi for crimes against humanity
27 May - G8 leaders call on Col Gaddafi to go
An African Union "roadmap", which was drawn up in February and called for an immediate ceasefire, was swiftly rejected by both the rebel Transitional National Council (TNC) and Nato because it did not call on Col Gaddafi to step down.
On Friday the G8 of leading industrial nations called for Col Gaddafi's departure. Russian President Dmitry Medvedev said on Saturday that the colonel no longer had the right to lead Libya.
The chairman of the Benghazi-based TNC, Mustafa Abdul Jalil, welcomed the statements, saying: "The entire world has reached a consensus that Col Gaddafi and his regime have not only lost their legitimacy but also their credibility."
But the Libyan government said it was not concerned by the G8's decisions.
"We are an African country. Any initiative outside the AU framework will be rejected," Deputy Foreign Minister Khalid Kaim said.
On Monday, rebel spokesman Guma al-Gamati told the BBC that he believed Mr Zuma's visit would make a difference as Col Gaddafi was far weaker and more isolated than he was last month.
"The people around him and the aides and people who are fighting for him are diminishing; some are deserting," he added.
Pro-Gaddafi forces, which control Tripoli and the rest of western Libya, have been targeted by Nato under the UN resolution aimed at protecting civilians.
Libyan state media said on Monday that Nato aircraft had killed 11 people at civilian and military sites in Zlitan, 50km (30 miles) west of Misrata.