The 19-year-old midfielder was a first-team regular at the San Siro when he joined the Serie A giants from Dinamo Zagreb last year, but he has since slipped out of contention for a starting berth under Walter Mazzarri.
As a result he looks set to leave this summer as Inter plan a massive transfer shake up following their recent takeover.
This has alerted Chelsea, United and Arsenal, who are all considering deals to bring him to England.
Kovacic is valued at around £12m, and it is thought that all three Premier League sides are willing to match that sum for the talented teenager.
Despite having sold Philippe Coutinho to Liverpool for what now looks like a bargain £8.5m in January 2013, Inter are willing to cash in on their youngster if their price tag is met.
United and Chelsea are also interested in Kovacic’s team-mate Fredy Guarin.
The Colombian midfielder has long been linked with a move away from the Milan side, but rumours have indicated that his employers are looking to tie him down to a new contract.