VfB Stuttgart management are tightlipped on a buyout clause in the contract of Serhou Guirassy.
The striker is interesting Everton and West Ham United.
Sports director Fabian Wohlgemuth told Sport1: I am not allowed to comment on contractual content.
"We'll see what happens in the future. We will definitely try everything to ensure that he stays for a long time."
Next summer, Guirassy's contract is said to see a 20m clause come into effect - a price below market value given the striker's current form (ten league goals in six games).