The investigation of Winterkorn announced on Monday was part of a "preliminary investigation" into Volkswagen, based on allegations made by unnamed people rather than on reasonable suspicion by law enforcement officers, the Braunschweig prosecutors' office said.

"There is currently no formal investigation against Winterkorn. The Braunschweig prosecution regrets that this impression may have been created as well as the irritation that (Monday's) press release caused," it said.

Winterkorn quit the top job at Volkswagen last week, after Europe's biggest carmaker admitted to cheating diesel emissions tests in the United States, sparking the worst business crisis in its 78-year history.

He said at the time that he was not aware of any wrongdoing on his part and wanted to give the company a new start.

(Reporting by Maria Sheahan; Editing by Mark Potter)