A Libyan official has cast doubt on claims a group of European tourists and their Egyptian guides seized in Egypt last week have been taken to Libya.
Searches of the border area had yielded no sign of the 11 tourists and their eight guides, the official said.
On Thursday, the Sudanese authorities said the hostages had been moved just over the border into Libyan territory.
They were seized last Friday while on a desert safari in south-western Egypt, near the borders with Libya and Sudan.
The group being held includes five Germans, five Italians and a Romanian
An unnamed Libyan foreign ministry official told reporters that the authorities had found no sign of the captives on Libya’s side of the border.
“With research operations now finished, we can confirm that the hostages and their abductors are not in Libya,” the AFP news agency quoted him as saying.
On Thursday, Egyptian officials had said the kidnappers were gangsters who were demanding several million dollars in ransoms.
A Sudanese foreign ministry official, Ali Yusuf Ahmed, meanwhile said its security forces had reported that the hostages were currently being held some 13km (8 miles) inside Libyan territory.
Mr Ahmed said the language of the kidnappers, and the direction they were originally taking, indicated that they could be part of a rebel faction from the western Sudanese region of Darfur.
Earlier this week, the captives were spirited into Sudan from the remote Egyptian region of Gilf al-Kebir, where they were seized.
The area, which is close to chronic conflict areas in western Sudan and eastern Chad, is sparsely populated and has virtually no police presence.
Gilf al-Kebir is a giant plateau famous for its prehistoric cave paintings, which featured in the 1996 Oscar-winning film, The English Patient.