Renault sacked the three managers in January, saying they had proof they had been selling secrets on technology which is expected to change the car industry.
Chief executive Carlos Ghosn went on French television channel TF1 to apologise "personally and in Renault's name”.
He said he had turned down an offer by operations chief Patrick Pelata to resign over the matter. Ghosn and Pelata will forgo their 2010 bonuses and Renault will review its security procedures and take disciplinary measures against three implicated security employees, Ghosn said.
Ghosn and Pelata said in a statement they would meet with the managers concerned as soon as possible and make reparations after revelations that the source of information alleging the spying may have been a fraudster.
Dominique Gevrey, who works in Renault security’s department, is expected to be charged after spending the weekend in the cells. Two other security employees were detained at the weekend, but were later released.
The car manufacturer said it would be a civil party in an investigation led by the Paris prosecutor into an organised gang.
The spying claims strained relations between France and China earlier this year.