Sassuolo insist Matteo Politano will only leave for big money.
AC Milan and Napoli remain keen on the midfielder.
“If we see the figures that have done the rounds, I think he's worth something big," Sassuolo chief Giovanni Carnevali told Gr Parlamento.
“He's certainly one of the best players in his position. €28m not enough? That was never a serious figure.
“A big offer is needed for him, but after that we'll need to make a decision with the club and player.
“Negotiations with Napoli? There was nothing special with them. Lots have been said, which don't correspond to the facts.
“He wanted to join Napoli, but we also had a desire to keep him. We've also shown in the past that we don't sell top players in January and we carried our ideas forward.
“Luckily Politano stayed with us, he's proving to be a great player and he's lifting us from certain problems.
“He's having an excellent season and big clubs may be interested in him, but we're happy to have kept him. He's behaved like a great professional.
“We have a good relationship with Napoli, but we haven't talked to them since. These are things that we'll address later. We'll make the right assessments and see which opportunities may arise."