The US said the meeting reiterated its demand that Col Gaddafi step down, and involved no negotiations.

A spokesman said the Libyan government supported dialogue with the US but only if it was free from preconditions.

On July 18, rebels said they had pushed government troops westwards after seizing back most of the town of Brega.

The Libyan government denied the claim, insisting that the key oil refinery town was still firmly under its control.

In a statement, the US state department said officials had given representatives of Col Gaddafi a "clear and firm" message that the Libyan leader had to go.

"The message was simple and unambiguous - Gaddafi must leave power so that a new political process can begin that reflects the will and aspirations of the Libyan people," it said.

The US did not give the location of the talks, but Libya said they had taken place on July 16 in neighbouring Tunisia.

Libyan government spokesman Moussa Ibrahim hailed the talks as an important step in "repairing relations" with the US.