United scout Jaap Stam has watched Walter a number of times this season.
He was impressed with the way the 19-year-old helped lead Brazil to their South American Under-20 Championship triumph earlier this year.
But despite his big reputation, Inter president Vitorio Piffero insists Walter and the rest of the club's exciting young prospects are going nowhere.
Piffero said: "He was a big success in the Under-20 competition with Giuliano and Sandro but there has been no offer.
"Every now and then, people want to sound things out but this hasn't happened.
"It's not our intention to sell him now."