Gevrey was detained on Friday as he prepared to board a flight for Guinea. Two other security employees were also questioned but have been released.
They were questioned about the identity of a supposed informer who accused three executives of selling company secrets. The three - Michel Balthazard, Bertrand Rochette and Matthieu Tenenbaum – were all fired in January but the case against them has appeared increasingly thin over recent weeks.
A Paris judge on Sunday opened an inquiry into fraud by an organised group.
Gevrey has reportedly claimed to be in contact with the alleged informer but refused to reveal his identity.
“He obviously doesn’t exist,” an anti-espionage police officer told the AP news agency.
Investigators have failed to unearth secret bank accounts that the executives were accused of opening in Switzerland and Liechtenstein.
The affair has become a major embarrassment to Renault bosses, Carlos Ghosn and Patrick Pélata.
Ghosn claimed to have overwhelming evidence of spying in January, while Pélata declared that details of its project to build an electric car had been leaked. Amid speculation that China was buying the information, President Nicolas Sarkozy’s government spoke of “economic warfare”.
In March Pélata was forced to recognise that the company might have been victim of a plot.
Renault’s lawyers on Sunday said they would not comment until after Gevrey had court appearance Monday.