Fiat CEO Sergio Marchionne reportedly said on Monday that a turnaround plan drawn up by the group's former management was "overly optimistic", but said the Italian automaker had the resources to complete it.

According to Reuters, Marchionne said in a slide presentation the 2003 plan was "crafted without assessing competitive response" and said Fiat's structure was inadequate to meet the plan's objectives.

Marchionne was appointed chief executive of Fiat at the beginning of June after his predecessor Giuseppe Morchio quit unexpectedly, the report added.