Senior members of deposed Libyan ruler Moammar Gadhafi's regime have fled to neighbouring Niger in a convoy of soldiers and vehicles, but Gadhafi is not believed to be with them, U.S. officials said Tuesday.

"We don't have any evidence that Gadhafi is anywhere but in Libya at the moment," U.S. State Department spokeswoman Victoria Nuland said, adding there was also no evidence his family members were in the group.

Niger customs official Harouna Ide said Gadhafi's security chief, Mansour Dao, was at the head of the convoy when it entered the capital Niamey early Tuesday. He said other Libyan convoys are south of Agadez, a town in central Niger, a desert country which borders Libya to the south.

Abdoulaye Harouna, an owner of a local newspaper in the northern Niger town of Agadez, said the convoy consisted of more than a dozen pickup trucks bristling with well-armed Libyan troops, said Harouna, who saw the arrival.

At the head of the convoy, Harouna said, was Tuareg rebel leader Rissa ag Boula, a native of Niger who led a failed war of independence on behalf of ethnic Tuareg nomads a decade ago. He then sought refuge in Libya and was believed to be fighting on behalf of Gadhafi.

Bani Walid ceasefire talks continue

Also Tuesday, tribal elders in a Gadhafi stronghold were trying to persuade regime loyalists holed up inside to lay down their arms, a rebel negotiator said.

Still, Gadhafi spokesman Moussa Ibrahim was defiant, insisting the former ruler is determined to fight his way back to power.

Gadhafi is "in excellent health, planning and organizing for the defence of Libya," Ibrahim told the Syrian TV station al-Rai, adding that both Gadhafi and his sons remain in Libya.

"We are fighting and resisting for the sake of Libya and all Arabs," Ibrahim said. "We are still strong and capable of turning the tables on NATO."

Gadhafi loyalists have been holed up in several towns, including Bani Walid, some 140 kilometres southeast of Tripoli. Thousands of rebel fighters have surrounded the town, as rebel leaders tried to negotiate a surrender deal.

Rebel negotiator Abdullah Kanshil said Tuesday that tribal elders in Bani Walid want assurances that the rebels will not take revenge, and are trying to persuade Gadhafi loyalists to lay down their arms.

A member of the rebel transitional council said by telephone Tuesday he was in a village near Bani Walid called al-Manasser that had just raised the rebel flag.

"We want the rest of the tribes to do like al-Manasser to avoid bloodshed and to realize that the regime is over and it will not come back," said Mubarak Sabah, who is from Bani Walid and represents the town on the transitional council.

"They should realize that their brothers around the country are enjoying freedom and that they can follow them."

Sabah reiterated that rebel fighters would not move into Bani Walid before Saturday unless the town surrendered, so as to avoid "a bloody war" with what he said was a minority of Gadhafi supporters in the town.

Gadhafi popular in north Niger

A volunteer, right, with the anti-Gadhafi forces repairs a weapon in Al-Noflea, the closest area to Sirte, about 450 kilometres from Benghazi. Sirte is one of Gadhafi's few remaining strongholds. (Esam Al-Fetori/Reuters)

Gadhafi's regime is believed to have financed the Tuareg rebellion in the north of Niger. African nations where Tuaregs represent a significant slice of the population, like Niger, have been among the last to recognize the rebels that ousted Gadhafi.

Gadhafi remains especially popular in towns like Agadez, where a majority of the population is Tuareg. The Sahara Desert market town is the largest city in northern Niger. Harouna says the pro-Gadhafi soldiers accompanying Boula were coming from the direction of Arlit.

The desert that stretches north of Arlit borders both Libya and Algeria. Some members of Gadhafi's family, including his wife, his daughter Aisha and two of his sons, recently sought refuge in Algeria.

A NATO official in Brussels said the alliance did not have any immediate information about the convoy. NATO warplanes don't normally patrol that deep south in the Sahara, the official said, speaking on condition of anonymity in line with standing alliance policy.

NATO spokesman Col. Roland Lavoie said the alliance's mission is to protect the civilian population in Libya, "not to track and target thousands of fleeing former regime leaders, mercenaries, military commanders and internally displaced people."

NATO reported bombing several sites overnight near Gadhafi's Mediterranean hometown of Sirte, a region NATO has targeted heavily every day in recent days.

Gadhafi's whereabouts are unknown, but speculation has centered on Sirte and the other loyalist holdouts of Sabha in the far south and Bani Walid.

The rebels hold most of Libya and have sketched out plans for a transition to democratic rule that would begin with a "declaration of liberation" that was likely to come before Gadhafi's strongholds are defeated and he is captured.