Sunderland boss Paolo di Canio is weighing up selling goalkeeper Simon Mignolet.
The Belgian has decided not to consider new contract talks this summer.
Mignolet's agent Guy Vendersmissen revealed: "I don't think at this moment we would be prepared to sign a new contract.
"When there is a new contract the team can block a player from moving.
"At this moment there are some clubs who are interested.
"But Simon still has a two-year contract so we depend on the position that Sunderland is taking in relationship to an eventual transfer."