The player has been linked with interest from Atletico Madrid, A.S. Roma as well as Leicester and West Ham.
Castro’s agent, Joseba Diaz is speaking to interested parties on behalf of his client before a decision is made.
The young defender famously scored away at Real Madrid in the quarter-finals of the Copa del Rey last year to knock the Spanish giants out of the competition.The Vigo-native’s contract at Estadio Balaidos runs until June 2019 but he is thought to be open to a move away.