The attacking midfielder has been given an ultimatum by his Dutch club to decide his future this week after City had a reported £4.8m bid accepted last month.
“He is a player we have shown interest in. But I have to say he is one of a few,” Hughton told the Pink 'Un. “Some of the reports that you will hear will have a little bit of substance to them, some are far off the mark but you learn in this game that until there is a done deal not to take anything for granted. But in general terms we are working very hard. In an ideal world you would like to do your business as soon as possible. The problem is it is getting more and more difficult for that to happen.”