Moammar Gadhafi's wife and three of his children fled Libya to neighboring Algeria on Monday, firm evidence that the longtime leader has lost his grip on the country.
Gadhafi's whereabouts were still unknown, and rebels are worried that if he remains in Libya, it will stoke more violence. In Washington, the Obama administration said it has no indication Gadhafi has left the country.
Rebels also said one of Gadhafi's other sons, Khamis, an elite military commander, was probably killed in battle.
The Algerian Foreign Ministry said in a statement that Gadhafi's wife, Safia; his sons Hannibal and Mohammed; and his daughter, Aisha, entered the country across the land border. It said Algerian authorities have informed the United Nations secretary-general, the president of the U.N. Security Council and the head of the Libyan rebels' government.
Ahmed Jibril, an aide to rebel National Transitional Council head Mustafa Abdul-Jalil, said officials would "demand that Algerian authorities hand [the Gadhafi family] over to Libya to be tried before Libyan courts."
Gadhafi's children played important roles in Libya's military and economic life. Hannibal headed the maritime transport company; Mohammed the national Olympic committee. Aisha, a lawyer, helped defend toppled Iraqi dictator Saddam Hussein at the trial that led to his hanging.
Ahmed Bani, the rebel council's military spokesman, said he was not surprised to hear Algeria welcomed Gadhafi's relatives. Throughout the six-month Libyan uprising, rebels have accused Algeria of providing Gadhafi with mercenaries to repress the revolt.
Over the weekend, the Egyptian news agency MENA, quoting unidentified rebel fighters, reported that six armored Mercedes sedans, possibly carrying Gadhafi's sons or other top regime figures, had crossed the border at the southwestern Libyan town of Ghadamis into Algeria. Algeria's Foreign Ministry had denied that report.
Bani said Monday that rebel forces may have killed Khamis Gadhafi in a clash Saturday with a military convoy near Tarhouna, 50 miles southeast of Tripoli, destroying two vehicles in the convoy. The bodies in the cars were burned beyond recognition, he said, but captured soldiers said they were Khamis Gadhafi's bodyguards.
"We are sure he is dead," Col. Boujela Issawi, the rebel commander of Tarhouna, told the Associated Press. But then he cast some doubt, saying it was possible Gadhafi's son was pulled alive from the car and taken to Bani Walid, a contested interior area.
Rebel leaders have started to set up a new government in the capital, Tripoli, after their fighters drove Gadhafi's defenders out over the past week. Gadhafi's whereabouts are still unknown, however, and people close to him have claimed he is still in the country and leading a fight to hold onto power.
"Gadhafi is still capable of doing something awful in the last moments," rebel leader Abdul-Jalil told NATO officials earlier Monday in Qatar.
The focus of concern is Gadhafi's hometown of Sirte, his last major stronghold. The town, 250 miles east of Tripoli, is heavily militarized and shows no signs yet of surrendering even though rebels say they are trying to negotiate a bloodless takeover.
There was some fighting Monday on the eastern and western approaches to Sirte. Gadhafi and senior regime figures may have fled there.
The rebels asked NATO Monday to keep up pressure on remnants of Gadhafi's regime.
NATO has been bombing Gadhafi's forces since March under a United Nations mandate to protect Libyan civilians.