A French state prosecutor was on Friday poised to launch an inquiry into industrial espionage at Renault after the carmaker filed a legal complaint alleging information was passed to a foreign power.
France's domestic intelligence service DCRI was expected to be officially charged with the investigation late on Friday or on Monday, sources close to the matter said.
Renault on Thursday set the scene for a lengthy judicial process by lodging a complaint on counts of organised theft, aggravated breach of trust and passing intelligence to a foreign power, Paris prosecutor Jean-Claude Marin said.
The move follows the suspension last week of three executives it suspects of leaking information about the high-profile electric vehicle programme in which it is investing heavily.
The carmaker said on Thursday it had discovered serious misconduct, detrimental to its "strategic, technological and intellectual assets".
Its complaint was against "persons unknown", implying all those involved may not yet have been identified.
Renault did not name the foreign power in its complaint, but did identify foreign private companies, Renault's lawyer Jean Reinhart said on Thursday.
Renault Chief Operating Officer Patrick Pelata has said the carmaker had fallen victim to an organised international network but key electric vehicle technology is safe.
The Paris prosecutor, who is linked to the state, can either open a preliminary investigation that he oversees, or a judicial inquiry that would be entrusted to an independent magistrate.
France could now be waiting months for clarity on a case that has gripped the country since the executives were suspended. Reinhart told Le Parisien on Friday an investigation of this kind would last at least six months.
France has dubbed the case "economic warfare" and is considering tightening up legislation to protect companies.
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.
The French government has played down the possibility of a link to China, saying it is not accusing any one country of involvement, while China has denied any link to the case.
Under French law, Renault had to wait 48 hours to send the dismissal letters after the hearing on Tuesday.