TRIPOLI, Libya — Rebel negotiators pressed fighters loyal to Col. Muammar el-Qaddafi in the town of Bani Walid to surrender on Tuesday, as a dozen senior members of his government fled the country in a convoy that crossed the southern desert into Niger, according to the State Department.

A flurry of confusing reports lent an air of mystery to the convoy and set off excited speculation among Libyan rebels that Colonel Qaddafi had fled the country — bringing joy that he could do no more harm here, and disappointment that he might have escaped Libyan justice — though by day’s end they were in doubt that he had fled.

The colorful and contradictory accounts from rebel leaders and officials of various countries seemed to reflect the unpredictability of the conflict and of the colonel himself, and the difficulty that rebel forces, preoccupied with securing Libya’s main cities near the Mediterranean Sea, face in trying to snare fleeing loyalists in the vast desert south.

Some versions said the convoy included more than 200 military vehicles, the kind of grand entourage that Colonel Qaddafi sometimes took on his travels. Others said it was made up mainly of Tuareg fighters who had sided with him as mercenaries or irregulars. Rebel leaders issued conflicting statements, with some saying one of his sons had fled with gold looted from the country’s banks.