Newcastle had tabled an £8million bid for De Jong, but the club want around £12m for the 21-year-old.
His agent Louis Laros: "I can only confirm that there has been interest from Newcastle in Luuk.
"I know that Newcastle are following him, that is no secret, but a club must first agree a fee with FC Twente and so far this has not happened. I really don't know what will happen next.
"It is not up to us at this moment, it is up to those clubs to show an interest and agree a financial deal with Twente.
"They are not the only club that has shown an interest, there has been a lot of clubs from all over Europe. More than five or six - but that is normal for a player who has scored 25 goals in the Eredivisie and is in the national side.
"It has got to be the right club for Luuk, and a club that Luuk likes. He has already rejected several clubs who are interested because they are not the right move. I can confirm that Newcastle are not one of the clubs that he has rejected.
"He would be the perfect fit for the Premier League. He is only young and there is no doubt about his quality - no-one is debating that.
"Now the most important thing is to find the right club for Luuk, which is what we will do."