Gadhafi's second wife, his daughter Aisha and sons Mohammed and Hannibal were among a group of 30 family members who fled to Algeria, the Tripoli Post reported Tuesday.
Acceptance of Gadhafi's wife and offspring has angered rebel leaders.
NTC Chairman Mustafa Abdul Jalil expressed his disappointment with Algeria, the only one of Libya's neighbors in North Africa not to have recognized the NTC as Libya's legitimate authority.
NTC spokesman Mahmoud Shamman said the council would seek to extradite the Gadhafis.
He said allowing the Gadhafis to enter Algeria amounted to an act of aggression.
"We are warning anybody not to shelter al-Gadhafi and his sons," Shamman said.