The 22-year-old has struggled to secure a place in the first team under Jose Mourinho, sparking reports that the Belgium international could leave.
De Bruyne joined the Blues from Genk in 2012, but spent last season on loan at Werder Bremen in the Bundesliga.
"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 regular at this point in time. We will definitely consider what is going on with him."
De Bruyne has started just two Premier League games so far this season.