The 22-year-old, who spent last season on loan in the Bundesliga with Werder Bremen, has struggled for opportunities with the London side this season, starting just two of their opening seven Premier League games.
"We, as a club, have given our signal of interest in the services of Kevin De Bruyne," Allofs told Sky Deutschland.
"This was done over the summer when it became obvious that he would be returning to Chelsea.
"Kevin De Bruyne is no first-team regelar at this point in time. We will definitely consider what is going on with him