Castaignos is currently at Dutch side Feyenoord, and has been reportedly tracked by Premiership sides Arsenal and Tottenham.
Treffers said: “For now the Nerazzurri manager (Rafael Benitez) is in Abu Dhabi, he should return next week and make a proposal to Feyenoord.
“At the time there was only some conversation between the two.
As for us, Luc would not mind staying at Feyenoord to continue to grow, but if the two clubs would reach an agreement, we would of course be ready to take a further step in his career.”
