Bernhard Schreier said at the company's annual general meeting last week that "many are looking" at the business following its 50% drop in share price over the past 12 months.
The chief executive said Russian investors could be interested in purchasing the company but warned that they may not be transparent in their intentions.
The German print giant has previously been linked with US investor Warren Buffet, but at the time, Schreier denied that there had been any formal approach.
Schreier hints at Heidelberg takeover approaches
Heidelberg's chief executive has said the company may be the subject of a takeover approach as its share price continues to fall.
