The 25-year-old has attracted the attentions of Galatasaray, and his representative has insisted that he is keen on the move after false quotes had claimed he was reluctant
The Dutchman is available on a free transfer after being released by Real Madrid and had been heavily linked with a move to Galatasaray.
However, Drenthe was distanced from the move by Fifa agent Tekin Birinci, who posed as the player's representative, but Kulup has insisted that his client is indeed interested in the transfer.
"I do not know why this gentlemen was posing as his agent, because Royston does not know him at all. The stories that the discussions would be with Kasimpasa and Kayserispor are not true," Kulup told Goal.com.
"It's really annoying because the big Turkish clubs that are interested are now thinking: 'Why is Drenthe in talks with those teams?' This only creates unrest and we don't want that.
"Turkey [is a favoured destination] because we are dealing with top clubs. Then there is the opportunity to play in the Champions League and that is what you want as a player.
"AC Milan also had an interest, but that ultimately failed. However, Serie A is a competition where Royston would like to play."
The 25-year-old spent last season on loan at Everton, but the Merseysiders decided against retaining his services following reported off-field issues.