A lawyer for one of the three Renault executives fired on suspicion of industrial espionage called on Renault Chief Executive Carlos Ghosn to make public on Sunday what proof he has against his client.

Ghosn, who is due on Sunday to give his first television interview since the scandal broke, earlier told the Journal du Dimanche newspaper that the carmaker had not broken any laws by conducting its own lengthy internal enquiry into the affair before making it public.

Ghosn did not, however, provide any specific details of the evidence against the three men, who have strongly denied any wrongdoing and say they plan to sue the company for damaging their reputations.

Pierre-Olivier Sur, one of the lawyers defending Renault's former vice president of advanced engineering, Michel Balthazard, said Ghosn should use Sunday's television appearance to come clean about the evidence against the three men.

Lawyer Xavier Thouvenin and myself call on the Renault chief executive to lay out the proof tonight, Sur told Reuters, noting Renault's investigation had been trigged by an anonymous letter. We are far, very far, from having any proof.

The lawyer said sources close to the investigation said it had uncovered payments to offshore bank accounts in Lichtenstein and Switzerland.

Therefore, these financial flows are traceable, Sur said, arguing that Renault as the plaintiff was not obliged to keep its evidence secret under French law. Let someone indicate these traces and we'll see it doesn't stand up, because my client has never had any offshore accounts. So there's a mistake.

In the newspaper interview published on Sunday, Ghosn declined to comment on whether Renault had enlisted a private agency to carry out its own investigations into the three executives.

All the information in our possession is today in the hands of judicial authorities, he said. I am not going to go into details here of what we did. But we have been irreproachable from a legal point of view.

Today, we are waiting for the justice system to do its work, Ghosn said, adding that this could take several months.

Ghosn said the leaked information was not about technology but rather the economic model Renault planned to use in the electric sector.

He said he had no conviction about who was the recipient of the information. Renault filed a legal complaint alleging that the information had been passed onto a foreign power, without saying which one.

The scandal has threatened to harm improving relations between France and China after a government source said intelligence services were looking into a possible connection with China as part of initial checks before the official probe.

Ghosn said Renault had been greeted with skepticism when it unveiled its electric car strategy in 2006 but was now the only carmaker producing its own electric motor, battery and charging system.

(Reporting by Gerard Bon; writing by Daniel Flynn; Editing by Matthew Jones and Will Waterman)