Libyan rebels are dismissing claims that they have held talks with aides to leader Moammar Gadhafi, as fighters have made recent gains in their push to oust his government from power.

The head of the rebel Transitional National Council, Mustafa Abdel Jalil, said Tuesday there have been no direct or indirect talks with Mr. Gadhafi's representatives, and that such talks are “unthinkable” unless the Libyan leader steps down.

Western news reports had said Mr. Gadhafi's aides met earlier this week with Libyan rebels and U.N. Libya envoy Abdul Ilah al-Khatib at a hotel on the Tunisian island of Djerba.

In Washington Tuesday, U.S. officials said Mr. Gadhafi's days are “numbered,” as rebels capture key towns to the south and west of the capital, Tripoli.

The rebels say they control most of Zawiya, a strategic town 50 kilometers west of Mr. Gadhafi's power base in Tripoli. Libyan officials deny the rebels have taken control of that town.

Rebel fighters entered Zawiya last week in their closest approach to the capital since the early weeks of the uprising.

Rebel officials say their fighters also captured the towns of Surman, 60 kilometers west of Tripoli, and Gharyan, 80 kilometers south of Tripoli. Those claims could not be independently verified. Control of Zawiya, Surman and Gharyan would allow the rebels to cut off Tripoli from a key highway to the south and another leading west to Tunisia.

In an audio message broadcast on Libyan state television Monday, Mr. Gadhafi urged his people to fight to “liberate Libya” from rebels who began their uprising in February to end his 42-year rule. He called the rebels “traitors” and denounced NATO as a “colonizer” for staging airstrikes in support of the uprising.