"I saw an exceptionally large and rare convoy of several dozen vehicles enter Agadez from Arlit... and go towards Niamey," the source said, amid speculation that toppled leader Moamer Kadhafi may be in it.
"There are persistent rumours that Kadhafi or one of his sons are travelling in the convoy," the source said.
A journalist from a private radio station in Agadez said he saw "a convoy of several dozen vehicles crossing the city and heading towards Niamey", the Niger capital.
The journalist said several people reported seeing in the convoy Rhissa Ag Boula, a figurehead Tuareg rebel in Niger who is close to Kadhafi.
Another Nigerien government source earlier said prominent regime officials had fled across the border on Sunday. They included Kadhafi's internal security chief Mansour Daw, who was earlier reported to be in the loyalist stronghold Bani Walid with at least two of the fallen strongman's sons.
Copyright AFP (Agence France-Presse), 2011