Saif Al-Islam at border
But he said Gaddafi's long-time heir apparent Saif al-Islam was set to flee Libya, with the NTC powerless to stop him.
"He's on the triangle of Niger and Algeria. He's south of Ghat, the Ghat area. He was given a false Libyan passport from the area of Murzuq," the official added.
He said Muammar Gaddafi's former intelligence chief Abdullah al-Senussi who, like Saif al-Islam, is wanted by the International Criminal Court, was involved in the plot.
"The region is very, very difficult to monitor and encircle," he said. "The region is a desert region and it has ... many, many exit routes."
The death of the fallen strongman allowed the NTC to trigger mass rejoicing by declaring Libya's long-awaited "liberation" on Sunday in Benghazi, the seat of the revolt.
But it also highlighted a lack of central control over disparate armed groups, and the jockeying for power among local commanders as negotiations begin in earnest to form an interim government that can run free elections.
"Leaders from different regions, cities, want to negotiate over everything - posts in government, budgets for cities, dissolving militias," said one senior NTC official in Tripoli, though he defended this as a healthy expression of freedom.
"Is that not democracy?" he asked. "It would be unusual if they did not after Muammar favoured only a few places for 40 years. There is no reason why it cannot be peaceful."
In Misrata, Libya's long-besieged third city, whose war leaders want a big role in the peace, fighters handing out surgical masks on Monday against the stench were still ushering hundreds of sightseers into the chill room where the bodies of Gaddafi, his son Mo'tassim and his former army chief lay on the floor, their flesh darkening and leaking fluids.