De Bruyne has spent all season in Germany on loan at Werder Bremen and he has impressed in the Bundesliga.
The Belgium international, who joined Chelsea from Genk in January 2012, is well down the pecking order at Stamford Bridge and has yet to make an appearance for the first team.
Chelsea are thought to be willing to offload De Bruyne this summer with reports in Germany claiming Dortmund are in pole position to land the midfielder.
Zorc was being non-committal on De Bruyne, but admitted he was an admirer of the player.
"I am not going to either confirm or deny this (agreement)," Zorc told Bild. "Kevin de Bruyne is under contract with Chelsea FC, he is a good player currently on loan at Werder Bremen."
De Bruyne admitted he is unsure where he will be playing next season after receiving several offers.
"I am receiving a lot of offers for next season," noted De Bruyne. "But I am not yet aware where I will play next term."