Volkswagen's attempts to leave its emission cheating scandal in the past have been dealt a blow as German prosecutors have broadened their investigation to include the chairman of its supervisory board, Hans Dieter Pötsch.

This probe relates to the release of information once the crisis hit - shareholders say that they were kept in the dark.

Following news that the company cheated emission regulators the company's stocks crashed - VW shares lost one quarter of their value.

Investors have taken legal action against the car firm for its management of investor-sensitive information as the debacle unfolded.

German authorities are already investigating the former VW chief, Martin Winterkorn.

Hans Dieter Pötsch was the firm's finance chief between 2003 and 2015 - he was involved in communicating the company's outlook to investors.

The 65-year old faces a maximum penalty of 10 years in prison.

VW is controlled by the Porsche and Piëch families, they have released a statement signalling their support for Pötsch - stating that he acted in accordance with the law.

The company said that its management, "duly fulfilled its disclosure obligation under German capital markets law."

Emission test rigging has led to a $15bn settlement in the US and the company's share price has never fully recovered.