* Ex-labour minister says Gaddafi power rests on money
* Says Gaddafi should remain in country, face trial
By Robert Evans
GENEVA, June 8 (Reuters) - Libya's defecting labour minister was reported on Wednesday as saying the Libyan government is selling oil on the black market as Muammar Gaddafi struggles to hold onto power.
Swiss media said Ali al-Amin Manfur told delegates at an International Labour Organization (ILO) conference on Tuesday that he was joining the Libyan rebels.
He told the Geneva daily Le Temps, in an interview published on Wednesday, that Gaddafi's remaining support came from people who had a financial interest in his survival.
"The regime controls the businesses, and the oil which it is selling on the black market, and it has access to the state treasury," said Manfur, who was the only delegate from Tripoli at the United Nations agency's two-week gathering.
He told Le Temps that Gaddafi had the backing of a maximum of 20 percent of the population, including the leader's own tribe. "But they are all armed, and most important of all they have the money," Manfur said.
He gave no details on oil sales in the interview, which appeared as Gaddafi's forces -- despite NATO bombing authorised by the United Nations to protect civilians -- began a new offensive against the rebel city of Misrata.
Under U.N. sanctions imposed on Libya in March over Gaddafi's violent reaction to demonstrations against his rule, five companies including the National Oil Corporation (NOC) and the central bank were blacklisted.
There was no formal oil embargo, but the blacklisting of NOC -- which had controlled the OPEC member's entire oil sector -- effectively made it illegal to buy Libyan oil.
In his interview, Manfur said he had decided to follow other ministers and top diplomats in walking out on Gaddafi after three months of trying fruitlessly to persuade the leader and his entourage to start a genuine dialogue with the rebels.
"There is no possible political solution with the members of the regime," he said. "The regime is dogmatic ... No one was able to tell Gaddafi that he is finished and that his sons have no right to govern the country after him."
Manfur, who told Le Temps he was leaving immediately for London and would then go on to Benghazi to offer his services to the rebels' Transitional National Council there, said Gaddafi and his sons should face trial in Libya for their crimes.
"If the regime falls, Gaddafi should not leave the country. He should remain in Libya to face the music," he declared. (Editing by Stephanie Nebehay and Tim Pearce)