Image caption Renault and its partner Nissan have invested extensively in electric vehicle technology

French carmaker Renault has said that suspected industrial espionage against its business poses a serious threat to its "strategic assets".

The statement comes a day after Renault suspended three senior managers after an investigation into the possible leaking of electric vehicle secrets.

Commenting on the matter, French Industry Minister Eric Besson warned the country was facing "economic war".

Mr Besson said the situation at Renault "appears serious".

"The expression 'economic war', while sometimes outrageous, for once is appropriate," he told France's RTL radio station.

"It appears to concern the electric car, but I do not want to go further."

Mr Besson said he was calling for French companies which received public funds to improve their security.

BBC business reporter Mark Gregory said that the French government was particularly concerned because of the important role carmaking plays in the French economy.

"Hundreds of thousands of French jobs depend on the motor trade," he said.

"The biggest advantage Western car makers have against rivals with lower labour costs elsewhere is their advanced technology. Hence the talk in France of an economic war."

Ethics alert

Analysis Industry bosses think electric cars will be the market's fastest growing sector over the next few years, and manufacturers are racing each other to get their vehicles into the showrooms. That means the technology behind the vehicles is particularly prized, with different manufacturers opting for different solutions. It's easy to see why corporate espionage could be tempting for some and disastrous for others. Renault's first electric car, the Fluence ZE, won't be available until the end of the year - so in that respect the carmaker is already behind some of its rivals. If its secrets have been stolen then that's going to make the situation worse. And technology will continue to be in demand. Many see the eventual future as being electric cars powered by hydrogen fuel cells, rather than a battery. And that's a whole new area for corporate thieves to get involved in.

Renault senior vice president Christian Husson told the AFP news agency that the people concerned were in a "particularly strategic position" in the company.

An investigation had uncovered a "body of evidence which shows that the actions of these three colleagues were contrary to the ethics of Renault and knowingly and deliberately placed at risk the company's assets", Mr Husson said.

One of the three suspended senior managers is a member of the carmaker's management committee.

The three have been given the opportunity to respond to the charges made against them, before the carmaker's human resources department decides on any sanctions.

Renault's investigation into alleged industrial espionage followed an "ethics alert" sent to its compliance committee.

The carmaker, alongside its partner Nissan, has invested heavily in electric vehicle technology.

Both plan to launch a number of new electric vehicles over the next two years.

They argue that pure electric vehicles are the best long-term solution to reducing carbon emissions from cars.

This is in contrast to rivals such as General Motors and Toyota, the world's two largest carmakers, which are instead investing heavily in hybrid vehicles, which use both an electric and a petrol engine.