TARHOUNA, Libya – Rebel fighters closed in Saturday on one of Moammar Gadhafi’s last strongholds, the remote desert town of Bani Walid, but were trying to persuade tribal elders there to surrender without a fight.

A rebel commander said the town has been given until today to surrender. “If they don’t raise the rebel flag tomorrow, we will enter with force,” said Abdel Razak al-Nathori, who commands one of the brigades advancing on Bani Walid.

Al-Nathori said one of Gadhafi’s sons, Muatassim, was in Bani Walid on Saturday, apparently to persuade tribal leaders to stick with the crumbling regime. Another Gadhafi son, Seif al-Islam, was in Bani Walid at some point but fled, said al-Nathori, speaking in the town of Tarhouna, about halfway between Tripoli and Bani Walid.

The elder Gadhafi remains a fugitive, and there has been much speculation about his whereabouts, with Bani Walid being named as a possible hiding place.

Abdel-Baset Naama, another rebel official from the area, said forces from various rebel-controlled towns were gathering along the approaches to Bani Walid. They have cut off access to the town from three directions, he said.

Rebels approached from the north to within six miles of the loyalist town, about 90 miles southeast of Tripoli. Rebel commanders said they would go no further, to avoid being accidentally targeted in NATO airstrikes.

Rebel forces are advancing toward a number of key loyalist targets, including Gadhafi’s hometown of Sirte and the southern loyalist stronghold of Sabha. The rebels have said, though, that they would prefer the towns surrender instead of taking them by force.

Bani Walid is a base of the million-strong Warfala tribe, which Moammar Gadhafi said would be among the tribes that would fight to the death for him.