Tuttosport says Inter will cough up €400,000 to land the 18 year-old defender.
Inter plan to immediately loan out Vagiannidis, who has agreed a five-year contract worth €100,000-a-season.
He will do preseason with Inter before being sent away to a rival.
Hellas Verona are regarded as favourites to take the youngster on-loan next season.
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!