Leeds forward Samuel Saiz is currently under investigation in Spain over alleged match fixing in La Liga, according to reports.
A spokesman for Spain's National Police has confirmed an operation is 'ongoing' with former Real Madrid player Raul Bravo also said to have been held.
He has been described by El Mundo as the suspected ringleader of a criminal organisation dedicated to gambling-motivated match-fixing of Spanish first and second division games.
Spanish police have confirmed they expect to arrest up to 11 people as part of their operation in tackling match-fixing, including current and retired first and second division players.