* Whereabouts of Gaddafi unknown
* NTC seek surrender of Gaddafi-held territory (Adds quotes from voice message)
CAIRO, Sept 1 (Reuters) - Muammar Gaddafi called on his supporters to set Libya ablaze, vowed his backers would not give up and said those against him were divided, according to an audio message broadcast on Arabic news channels on Thursday.
"They want to enter a long battle with us. Let it be a long battle. We will fight from place to place, from town to town, from valley to valley, from mountain to mountain," Gaddafi said in his message.
"If Libya goes up in flames, who will be able to govern it? Let it burn. They don't want to rule Libya. They cannot rule it as long as we are armed. We are still armed. We will fight in every valley, in every street, in every oasis, and every town."
Gaddafi's whereabouts were a mystery. He gave no indication of where he was in his audio remarks.
A Libyan military chief said Gaddafi was believed to be in Bani Walid outside Tripoli planning a fight-back. An Algerian newspaper has reported him to be in the border town of Ghadamis.
The ruling National Transitional Council (NTC), which ousted him, is seeking the surrender of Gaddafi's coastal home town of Sirte and other areas loyal to him.
Gaddafi said tribes in Bani Walid, Sirte and other areas of the country were armed and could not be subdued. He said those fighting against him were divided and called on tribes in Tripoli to ambush his opponents.
"How can we give ourselves up again? Are we women surrendering ourselves to our husbands or what?" he said.
"The colonisation must end," he said, adding: "Every tribe controls an area of Tripoli and is fighting this weak occupation. You are stronger than them," he said.
Details of his comments were first carried in brief headlines on Al Arabiya and the Syrian-owned channel Arrai before the tape was broadcast. The audio message was broadcast afterwards.
Gaddafi said those against him "are plotting to destroy Libya to seize Libya's petrol and its sovereignty."
"It is clear that the colonisers are using technical means to silence my voice ... But that shows that the occupation is weak and hides the truth," he said.
In earlier headlines carried by Arrai television, Gaddafi was quoted as saying: "Even if you don't hear my voice, continue resistance." (Reporting by Omar Fahmy; Writing by Edmund Blair; Editing by Matthew Jones)