The Dutch ace is expected to leave the Eredivise in the summer.
"I know that the player is liked by Milan, but we are only at the early stage. In the sense that there has never yet been a second step," agent Chiel Dekker told MilanNews.it.
"But I guess for any move from any club it is too early, on the other hand we are in March and the winter transfer window has just ended. I think it is more appropriate to address the topic in April or May."