The Belgian international has enjoyed a successful season at Werder Bremen in the Bundesliga and has caught the eye of both Dortmund and Leverkusen.
"He still has a few talks to hold with Chelsea," Holzhauser told Kicker. "It looks like there is an offer from Dortmund to sign the player for a relatively high fee.
"According to our information, Chelsea don't want to sell him but just loan him out."
However, Leverkusen are yet to speak with De Bruyne to "find out if he actually wants to come to us and, if so, on what conditions."
De Bruyne has 11 caps for Belgium.