TARHOUNA, Libya – Convoys of Moammar Gadhafi loyalists, including his security chief, fled across the Sahara into Niger on Tuesday in a move that Libya’s former rebels hoped could help lead to the surrender of his last strongholds.

Still, efforts to negotiate the peaceful handover of one of the most crucial of those bastions, Bani Walid, proved difficult.

Tribal elders from Bani Walid who met Tuesday with former rebels were confronted by angry residents of the city, including Gadhafi supporters, who fired in the air and sent them fleeing, mediators said. Many in Bani Walid remain deeply mistrustful of the forces that have seized power in Libya and are reluctant to accept their rule.

Some former rebels depicted the flight to Niger as a major exodus of Gadhafi’s most hardcore backers. But confirmed information on the number and identity of those leaving was scarce as the convoys made their way across the vast swath of desert — over 1,000 miles — between populated areas on the two sides of the border.

Gadhafi himself is not in the convoys, the U.S. State Department said.

As the first group of a dozen vehicles pulled into Niger’s capital, Niamey, a customs official said it included Mansour Dao, Gadhafi’s security chief and a key member of his inner circle, as well as around 12 other Gadhafi regime officials.

The official, Harouna Ide, told The Associated Press other Libyan convoys had passed through Agadez, a town about halfway between Niger’s border with Libya and its capital in the far southwest.

The convoys included heavily armed contingents of Tuareg tribal fighters from Niger, who have long been enlisted as mercenaries for Gadhafi’s regime, Niger officials said. A Gadhafi opponent said it was also carrying gold and cash belonging to the regime.

U.S. State Department spokeswoman Victoria Nuland said the U.S. has urged Niger to detain anyone who might be subject to prosecution in Libya, confiscate weapons and impound any state property such as money or jewels that were illegally taken out of the country.

Nuland said some senior members of the Gadhafi regime were in the fleeing group, but not Gadhafi or his family.

The West African nation of Burkina Faso, which borders Niger, offered Gadhafi asylum last month, raising speculation the convoys were part of plan to arrange passage there for the ousted leader. But on Tuesday, Burkina Faso said he would be arrested if he came there.