An informer behind allegations of spying on French car maker Renault that fizzled out for lack of evidence was paid a quarter of a million euros, the company's lawyer said Wednesday.

The case saw three top managers sacked in January on suspicion of leaking secrets of electric cars, and drew an angry denial from China which was accused of industrial espionage in a case the government branded "economic warfare."

But it all appeared to come to nothing this month when a source close to the investigations told AFP that police had drawn a blank in probing the spying allegations.

The source said police had found no trace of Swiss bank accounts the accused men were alleged to have held.

"As part of an audit and the gathering of invoices, it seems that a sum of about 250,000 euros (350,000 dollars) was paid" to an anonymous informer, Renault's lawyer Jean Reinhart told AFP Wednesday, confirming a press report.

He said the money was paid by an investigator working with Renault to an unnamed informer who fuelled the allegations against the managers.

The newspaper that broke the story, investigative weekly Le Canard Enchaine, said the informer was demanding further payments to provide proof for the allegations, but Reinhart denied this.