A Syrian television station has aired an audio message purportedly from ousted Libyan leader Moammar Gadhafi, who slammed reports that he may have fled Libya in a convoy to neighboring Niger.

In the comments broadcast Thursday on Al-Rai TV, Mr. Gadhafi called the reports “lies” designed to destroy morale and insisted he is still in Libya. He said his supporters will defeat NATO and are ready to fight transitional authority forces in the capital, Tripoli.

The National Transitional Council has sent envoys to Niger in an effort to prevent Mr. Gadhafi and associates from escaping justice by fleeing across the border. Mr. Gadhafi's whereabouts are not known, and Niger's government says the former strongman is not in the country.

Officials in Niger say they are acting in consultation with the NTC and that Libyan convoys that recently crossed the border were much smaller than reported.

In Tripoli, the new governor of Libya's central bank said Mr. Gadhafi sold about 20 percent of the country's gold reserves in the final days of his rule. Since April, Qassim Azzuz said the former government sold 29 tons of gold, worth $1.4 billion, to local merchants to pay salaries.

Meanwhile, U.N. Secretary-General Ban Ki-moon said Thursday the transition process in Libya cannot move backwards, and the United Nations will continue to help the Libyan people reach their aspirations of human rights and democracy.

NATO said Thursday its warplanes bombed five armored vehicles near Mr. Gadhafi's hometown, Sirte, as well as 18 surface-to-air missile systems around the town of Waddan, about 300 kilometers to the south.

Near Bani Walid, a desert town held by Gadhafi supporters, negotiators from Libya's National Transitional Council say they are committed to avoiding bloodshed as they press tribal elders tied to the former leader to surrender.