Muammar Gaddafi's second wife, two of his sons and his daughter have entered Algeria, according to the Algerian foreign ministry.
"The wife of Muammar Gaddafi, Safia, his daughter Aisha, and sons Hannibal and Mohammed, accompanied by their children, entered Algeria at 08:45am local time [0745GMT] through the Algeria-Libyan border," the ministry said in a statement on Monday published by the APS news agency.
However, it gave no information on the toppled Libyan leader, whose whereabouts has remained a mystery since fighters opposed to his government seized control of Tripoli, the Libyan capital, last week.
Algeria said their arrival had been reported to the United Nations and to the head of Libya's Transitional National Council [NTC], now widely recognised internationally as the country's legitimate government.
But an NTC spokesman accused Algeria, Libya's western neighbour, of an act of aggression and said the council would seek the extradition of Gaddafi's family members.
Ahmed Bani, a military spokesman for the council, said he was unsurprised to hear Algeria had welcomed Gaddafi relatives.
Throughout the six-month Libyan uprising, rebels have accused Algeria of providing Gaddafi with mercenaries to curb the revolution.
Al Jazeera's Anita McNaught, reporting from Tripoli, said: "There have been rumours over the last few days that family members had gone and that Gaddafi himself may have gone.
"The Algerian government has always got on really well with the Gaddafi regime. Algeria is one of the few countries that has not yet recognised the NTC."
Earlier, the Egyptian news agency MENA, quoting unidentified rebel fighters, had reported that six armoured Mercedes cars, possibly carrying Gaddafi'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.
ICC warrant against Khamis?
Meanwhile, Khamis Gaddafi, another of Gaddafi's sons, whose military unit is accused of killing dozens of detainees in Tripoli, may be placed on the international war crimes court's most-wanted list, the prosecutor told Reuters on Monday.
The Hague-based International Criminal Court [ICC] has already approved warrants for the arrest of Gaddafi, his son Saif al-Islam, and Libyan intelligence chief Abdullah al-Senussi on charges of crimes against humanity.
Luis Moreno-Ocampo, the ICC prosecutor, said he may also apply for an arrest warrant for Khamis, after Human Rights Watch said members of the Khamis Brigade, a force commanded by him, appeared to have carried out summary executions of detainees whose bodies were found in a warehouse in Tripoli.
"We know Khamis should also be prosecuted because he was the commander of the brigade that was more active on some of the crimes," Moreno-Ocampo said.
Moreno-Ocampo said a UN Human Rights Council commission would conduct further investigations on the ground in Libya soon and that he would base his decisions on the results.
There has been footage of mercenaries with nothing in their passports but stamps into Algeria, and the government has been noticeably silent on recognizing the NTC.
This is also not likely to be a popular decision (to put it mildly). Wondering why, given events of the past 6 months, the government decided to do it anyway.
Added link: El Watan has reported that Algeria has unilaterally closed the border with Libya. Original in French (I don't think they have an English-language page, and it's not elsewhere); this is my so-so translation, anyone with better French please correct me:
This is a general alert to the/for the [?] Algerian-Libyan border. We have learned from reliable sources that the Algerian state has unilaterally decided to close its borders with Libya.
A communiqué should be issued to different departments with responsibility for enforcement on the borders such as the National Popular Army (ANP), the Gendarmerie Border Guards (GGF), the border police, and Algerian customs.
According to diplomatic sources in Algiers, who confirm the information, this concerns the extreme south of the border only.
The closure comes after the announcement by the Ministry of Foreign Affairs of the entry into Algeria of several members of the family of El Kadhafi.