It is no secret that the Dutch midfielder is looking to leave the Neroazzurri in January following a contract dispute with the club, and Inter are willing to sell if the price is right.
PSG, Manchester United and Tottenham are all reportedly keen, while Bundesliga side Schalke also appear to have joined the race.
The Miners showed a real testament of their ambition by persuading star striker Klaas Jan Huntelaar to sign a contract extension despite the heavy interest from abroad.
Schalke now want to pair the highly rated goalscorer with his international teammate as they plan to build a side capable of challenging for honours on domestic and international stage.
It is believed that an offer in the region of €15 million could do the trick, but if nothing else works the Miners will try to include youngster Julian Draxler in the deal.