"We certainly made strong enquiries (for van Wolfswinkel) but the figures that came back were way above what we would be prepared to pay," he said. "What I would say is the conversations we had with Celtic were always done the right way and the same for the responses we got back.
"At this moment that door is closed, but we don't know. We'll see what the situation is in the summer. Our approaches were done in the correct manner. They decided they didn't want to sell and it is part of the game. You might want their player but ultimately they have the final say and there is genuine respect between the two clubs."