Updated at 4:23 p.m. ET
TRIPOLI, Libya - Muammar Qaddafi'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.
Qaddafi'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 Qaddafi has left the country.
Rebels also said one of Qaddafi's other sons, elite military commander Khamis, was probably killed in battle.
The Algerian Foreign Ministry said in a statement that Qaddafi'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 transitional leadership council.
Ahmed Jibril, an aide to rebel Transitional National Council head Mustafa Abdul-Jalil, said officials would "demand that Algerian authorities hand them over to Libya to be tried before Libyan courts."
Qaddafi'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 in the defense of toppled Iraqi dictator Saddam Hussein in the trial that led to his hanging.
Ahmed Bani, military spokesman of the council, said he was not surprised to hear Algeria had welcomed Qaddafi's relatives. Throughout the six-month Libyan uprising, rebels have accused Algeria of providing Qaddafi with mercenaries to repress the revolt.
Over the weekend, the Egyptian news agency MENA, quoting unidentified rebel fighters, had reported that six armored Mercedes sedans, possibly carrying Qaddafi'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.
Rebel military spokesman Ahmed Bani said Monday that rebel forces may have killed Khamis Qaddafi in a clash Saturday. Rebel clashed with a military convoy in the town of 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 Qaddafi's bodyguards.
"We are sure he is dead," Col. Boujela Issawi, the rebel command of Tarhouna, told AP. But then he cast some doubt, saying it was possible Qaddafi'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 Qaddafi's defenders out over the past week. Qaddafi'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.
"Qaddafi 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 Qaddafi's hometown of Sirte, his last major stronghold in the country. 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. Some have speculated that Qaddafi and other senior regime figures may have fled there.
A NATO officer, who asked not to be identified because of alliance rules, said there was fighting 30 miles east of Sirte. He said there are still clashes around Sirte, Bani Walid south of Misrata and Sebha further south.
Taking Sirte will mean getting past entrances that are reportedly mined and an elite military unit. Qaddafi's tribe is the most powerful in the city. Libyans familiar with the coastal city on which Qaddafi has lavished building projects say its first line of defense is a heavily fortified area called the al-Wadi al-Ahmar, 55 miles to the east.
The rebels asked NATO Monday to keep up pressure on remnants of Qaddafi's regime.
"Even after the fighting ends, we still need logistical and military support from NATO," Abdul-Jalil said in Qatar. NATO has been bombing Qaddafi's forces since March under a United Nations mandate to protect Libyan civilians.
In other developments, the chairman of the African Union on Monday accused Libyan rebels of indiscriminately killing black people because they have confused innocent migrant workers with Qaddafi's mercenaries. Jean Ping, speaking to reporters in Ethiopia, added this is one of the reasons the AU is refusing to recognize the Transitional National Council as Libya's interim government.
Ping charges are much stronger than any that have been levied at the rebels by international rights groups. The groups have, however, expressed concern about beatings and detentions of immigrants from sub-Saharan Africa.
Qaddafi had recruited fighters from further south on the continent, but many sub-Saharan Africans are in the country as laborers.
Transitional National Council spokesman Abdel-Hafiz Ghoga denied the AU claims.
"These allegations have been made during the early days of the revolution. This never took place."