Aldo Costa has revealed he is unhappy with Ferrari’s comments in the wake of his departure last year.
The Italian was stepped down as the famous team’s technical director, and he switched to Mercedes before the German marque made a significant step forwards with its 2012 car.
He has remained quiet about his treatment by Ferrari until now, telling Autosprint magazine that the Maranello marque lacked "style and professionalism" as it handled its restructuring.
Asked for more information, he said Ferrari explained "things that not only myself but also the whole world of formula one knows is not the truth".
Costa confirmed that he was referring to Ferrari’s suggestion that he lacked "creativity".
Still, he said he is not happy to see his old team struggling to make it into Q3 with the aggressive F2012.
"I still have so many friends in Maranello, but now I want to be 100 per cent engaged on succeeding with Mercedes."
He said the Ross Brawn-led team has a "different" approach to Ferrari’s "that makes it easier to do things".