Prosecutors in Braunschweig, Germany, say they are investigating Volkswagen AG's supervisory board chairman Hans Dieter Poetsch over suspected market manipulation. 

The probe announced Monday focuses on whether Volkswagen manipulated markets in 2015 by delaying the release of information about the financial impact of its emissions test-cheating scandal. New questions have also arisen about the scandal.

That's after California regulators discovered vehicles sold by VW's Audi luxury brand had software that improperly reduced emissions during government tests.

The discovery's potential impact on Volkswagen's efforts to resolve its emissions scandal was unclear.