"Talks took place during last night at a Djerba hotel under heavy security," a source close to the Tunisian security services told AFP. "Corteges of cars on Sunday crossed the border at Ras Jedir, near Djerba", the source added, asking not to be named.
At the same time, a South African jet and two Qatari military helicopters were on the tarmac at the airport of Djerba, a south Tunisian island close to the border with Libya, an airport source told AFP.
Libyan Health Minister Ahmed Hijazi and Social Affairs Minister Ibrahim Cherif stayed in Djerba on Sunday, where they were joined by Foreign Minister Abdelati Obeidi, the national TAP news agency said.
Negotiations were under way with "several other foreign parties", the agency added, without giving details of the content of the talks.
Clashes took place during the night at Ben Guerdane, near Ras Jedir, between Libyans who support Gaddafi and Tunisians who had crossed the border in large 4x4 cars to join Libyans celebrating "the end of Gaddafi", according to residents.
The supporters of Gaddafi had celebrated what they saw as a victory in the streets, according to a witness who gave his name as Mohamed.
The clashes ended at around 2:00 am (0100 GMT) when Tunisian units of the Service for the Protection of Public Order (POB) moved in, he added.
Special military reinforcements and unusual activity were noted on Sunday at Ras Jedir, on the Libyan side of the border, while a number of injured people arrived in Tunisia via Saharan tracks, witnesses said.
"There are an unprecedented number of vehicles of security forces backing Gaddafi, with tanks and heavy armour on the Libyan side of the border post," said a witness who asked not to be named.
In Tunis, the Libyan embassy was surrounded by barbed wire and a heavy military guard. The extra protection was provided after Libyan rebel supporters tried to put up their flag on a main street in the capital.
A large number of prominent Libyans on Sunday booked into luxury hotels in the northern Gammarth suburb of Tunis, where Foreign Minister Obeidi stayed last week, hotel industry sources said.
Gaddafi on Monday spat defiance at "the rats" and "the coloniser," meaning the Libyan rebels and NATO, after the insurgents claimed control of key towns near his capital Tripoli.
He predicted a swift end for his foes.