Cagliari are prepared to sell Radja Nainggolan this month.

The Belgium international has been linked with AS Roma and Inter Milan.

"Nainggolan is worth more than €15m," Rossoblu sporting director Nicola Salerno told Sport Italia. "Only President Massimo Cellino knows the precise figure.

"However, it is pointless talking about it right now as there are no negotiations taking place. There is time though.

"We are not interested in any player plus cash deals though. If someone wants Nainggolan then he will cost that much."