The French government today said it was the victim of an "economic war" after Renault, the partially state-owned car maker, suspended three top executives over suspected leaks of secret electric car technology.

The French industry minister, Eric Besson, told French radio: "The expression 'economic war', while often outrageous, is for once appropriate here." He said the case illustrated "the risks our companies face in terms of industrial espionage, and economic intelligence".

Renault has launched the biggest industrial espionage investigation in its history. The three executives were escorted from their offices at Renault's technical centre outside Paris on Monday. They had been under investigation for months over breaches of "ethics". Renault has revealed little detail but the French media has named the three executives. They include Michel Balthazard, a senior member of the management committee for 30 years, who had access to highly sensitive material about Renault's cars of the future. Another suspended manager worked exclusively on electric cars.

Renault said today that the investigation concerned people in "strategic positions" who had "consciously and deliberately put at risk company assets".

There was shock at Renault's technology headquarters, where over 1,000 engineers are devoted to developing electric car technology in top secrecy. One told Le Figaro it was a "living nightmare".

Renault has been tight-lipped over what information was leaked, but Besson confirmed it appeared to involve the flagship electric car project.

Renault and its Japanese partner Nissan have jointly invested €4bn in the race to produce electric cars for the highly competitive international market. The company's bosses believe electric cars could represent 10% of the market in 2020, given pressure to cut carbon emissions.

Renault will release its first battery-powered electric cars this year, the Fluence and the Kangoo Express. Two others are being finalised, the Zoe, a small family hatchback, and the smaller Twizy.

Renault is about to file around 30 patents for electric car technology and has 100 more in development. It is understood to be focusing on pure electric cars, as opposed to its competitors' hybrid electric and petrol cars.

The technology is a challenge, with companies competing to develop a battery that does not have to be repeatedly replaced and recharged or to find an alternative to the electric battery. Renault is staking its future on massive investment in battery-technology to gain an edge over its Chinese, American, Korean and German competitors. French media speculated that the espionage could involve either secrets being given to competitors or to companies which provide car batteries.

France's car industry directly or indirectly employs 10% of the active population and is crucial to its economy. The three executives, if found to have leaked information, could be dismissed in the coming days.

France has been worried about attacks on its industrial secrets for some years, after a spate of industrial espionage cases involving companies such as the tyre-maker Michelin and car-component group, Valeo.