The 24-year-old has three years remaining on his current deal with the Potters and the club insist they are under no pressure to sell the former Blackburn man.
Stoke are 3/1 with Paddy Power to be relegated next season
"There haven't been offers that I am aware of, but we wouldn't stand in his way if Real Madrid or a club of a similar standing came in for him.
"He has said he has designs to play at the highest level. He needs to play well to attract these clubs and I hope he does. He is a good player and the ball is in Mark Hughes' court."
N'Zonzi left Blackburn in similar circumstances following their relegation two seasons ago, with Stoke handing him a route back into the Premier League.
His performances last season earned him the club's Young Player of the Year award, as he scored one goal in 35 Premier League appearances for the Potters.