The US State Department has said it does not believe Colonel Muammar Gaddafi was travelling in a large military convoy that crossed the desert frontier into Niger from Libya earlier this week.
It is thought the convoy of up to 250 vehicles transporting pro-Gaddafi forces was escorted to the northern city of Agadez by units from Niger's army.
The US said it believed the convoy was carrying senior members of Gaddafi's entourage and urged Niger to detain anyone liable for prosecution for alleged crimes committed during the uprising against the deposed Libyan leader.
US Defence Secretary Leon Panetta said yesterday Gaddafi was ''on the run".
When asked later if he thought Gaddafi was still in Libya he said: "You know, I don't know. I think he's been taking a lot of steps to make sure that in the end he could try to get out if he had to, but as to where, when, and how that'll take place, we just don't know."
Gaddafi's spokesman Moussa Ibrahim said he had not left.
"He is in Libya. He is safe, he is very healthy, in high morale," he told Reuters by telephone from an undisclosed location.
Anti-Gaddafi forces that overthrew the long-serving ruler two weeks ago said they also thought about a dozen other vehicles that crossed the border may have carried gold and cash apparently looted from a branch of Libya's central bank in Gaddafi's home town.
France, Niger and Burkina Faso, as well as Libya's new rulers and NATO, all denied knowing where Gaddafi was or of any deal to let him go abroad or find refuge from Libyans and the International Criminal Court, which wants to put him on trial for war crimes.
"To my knowledge, there have not been hundreds of vehicles that crossed into Niger," Niger's Interior Minister Abdou Labo told a news conference.
He did confirm reports that Gaddafi's security chief Mansour Dhao had been allowed to enter the country.
Mr Labo said this was on humanitarian grounds and that Mr Dhao was the only Libyan official received.
