AZ Alkmaar are demanding Afonso Alves, the Middlesbrough forward, pays them £5.9 million after they claimed he broke an agreement to join them.

The Dutch club say Alves had agreed, in principle, to join them during the January transfer window, but the Alkmaar club failed to reach a deal with Heerenveen, Alves' previous club, by December 31 and the player instead decided to move to Teeside.

However, Middlesbrough have now advised AZ Alkmaar to direct their claim for compensation over their failed bid to Heerenveen and not the player. A spokesman said: "We believe this is a matter between Heerenveen and AZ and that Afonso should not even be involved."

The case between AZ and Alves has now gone to arbitration and Eric Vile, the Dutch club's lawyer, said: "We are claiming this amount of money on the basis of FIFA's rules."

The hearing will continue on May 19.