Mario spent the second half of last season on loan at West Ham United - scoring twice in 13 Premier League appearances for the Hammers.
The Portugal international is currently on holiday following the 2018 World Cup, but Inter are keen to sell ahead of the 2018-19 campaign.
Wolves have been strongly linked with a move, but according to La Gazzetta dello Sport, Inter have informed the Premier League outfit that it will cost them £24m to sign the 25-year-old on a permanent deal.
As a result, Wolves will have to break their transfer record for the second year running if they wish to bring the attacker to Molineux in this summer's transfer window.
Wolves are next in pre-season action against Dutch giants Ajax on Thursday afternoon.