The 28-year-old spent the recently concluded campaign on loan at Belgian club Zulte Waregem and made 32 appearances across all competitions for them.
Despite De Bock impressing during his time at Zulte Waregem, the club decided against taking up the option to make the defender’s loan move permanent.
However, the Belgian Pro League club remain interested in retaining De Bock’s services beyond his loan contract and are hopeful of striking a fresh deal with Leeds.
According to Belgian daily Het Laatste Nieuws, Leeds and Zulte Waregem are in negotiations over a permanent transfer for the defender.
Leeds, Zulte Waregem and De Bock are keen to see the transfer go through and are expecting to reach an agreement on a deal soon.
The Belgian, who has been on the Whites’ books since January 2018, was involved as Zulte Waregem began pre-season training on Wednesday.
With Zulte Waregem not exercising the option to buy De Bock, it is possible that they are trying to negotiate a lower transfer fee with Leeds.