Inter chief operating officer Marco Fassone has confirmed that the Nerazzurri are taking Sunderland to FIFA over non-payment over midfielder Ricardo Alvarez.
The Nerazzurri loaned Alvarez to Sunderland last season and claim a clause was inserted into the deal which would compel the Black Cats to keep him permanently if they survived in the Premier League.
A set sum was cited and Inter were expecting the first installment of the fee from the Premier League side for the midfielder.
But it did not arrive and now Inter are launching legal action by taking the case to FIFA, while they will also claim damages for the Black Cats' conduct in the case.
Fassone was quoted as saying by Italian outlet Calcio Mercato: "We have appealed to FIFA as Sunderland had a deal with a redemption clause in the case of avoiding relegation and have not respected it.
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"We have called for the agreement to be respected and also for damages for their behaviour."
Alvarez found his Premier League appearances for Sunderland severely restricted last season as he struggled with knee problems throughout the campaign.
However, Inter believe Sunderland have no option but to sign the Argentine on a permanent deal.
