Fiat Chrysler said it knew nothing about the medical condition of Sergio Marchionne after a Swiss hospital said on Thursday it had been treating the deceased chief executive for more than a year.

"Due to medical privacy, the company had no knowledge of the facts relating to Mr. Marchionne's health," a Fiat Chrysler spokesman said.

Questions have been raised about how long Marchionne, who died on Wednesday, was ill and how much the company knew before it made the situation public.

Marchionne rescued Fiat and Chrysler from bankruptcy after taking the wheel of the Italian carmaker in 2004 and he multiplied Fiat's value 11 times through 14 years of canny dealmaking. He was due to step down at FCA in April next year.

"The company was made aware that Mr. Marchionne had undergone shoulder surgery and released a statement about this," the spokesperson said.

"On Friday July 20, the Company was made aware with no detail by Mr. Marchionne's family of the serious deterioration in Mr. Marchionne's condition and that as a result he would be unable to return to work. The Company promptly took and announced the appropriate action the following day."