Serie A - 'Arsenal target' Alvarez joins Inter
"The deal is for about $17 million (£10.64m) for 90 per cent of the economic rights (over the player) with the remaining 10 per cent being held by this club," Velez said on their website.
Velez added that after the 23-year-old has made 80 appearances for Inter they can choose to buy him outright for another 1 million euros (£894,000) or allow Velez to retain their 10 per cent for future deals.
Nicknamed "Ricky Marvel", Alvarez is a product of the Velez youth scheme and made his first team debut in 2008 but a knee ligament injury curtailed his appearances prior to this season.
He helped the club win their eighth league title in the Clausura championship, scoring three goals in 14 appearances, and reach the semi-finals of the South American Libertadores Cup.