Inter requested FIFA arbitration over Sunderland’s refusal to buy Ricky Alvarez on a permanent basis.
The creative midfielder had moved on loan with an €10.5m (£7.5m) option to buy that would become mandatory if Sunderland avoided relegation from the Premier League.
The one-season loan itself also cost Sunderland €1.5m.
However, the Black Cats are refusing to pay the buy-out clause because of a knee injury that eventually required surgery.
Inter requested FIFA arbitration over Sunderland’s refusal to buy Ricky Alvarez on a permanent basis.
The creative midfielder had moved on loan with an €10.5m (£7.5m) option to buy that would become mandatory if Sunderland avoided relegation from the Premier League.
The one-season loan itself also cost Sunderland €1.5m.
However, the Black Cats are refusing to pay the buy-out clause because of a knee injury that eventually required surgery.
Alvarez only managed 13 Premier League appearances, three in the FA Cup and one in the League Cup for a grand total 728 minutes of football.
Inter are furious and, according to several sources, presented their appeal to FIFA for arbitration.
As things stand, neither club wants the Argentine in their ranks for this season.