Cagliari president Massimo Cellino has put an €18 million price tag on highly-rated midfielder Radja Nainggolan.

The 24-year-old has been strongly linked with a move to Serie A champions Juventus.

"I promised Radja that should an offer from a top club arrive, I would allow him to leave," Cellino said to Corriere dello Sport. "But the offer needs to be a big one, not inferior to €18 million."

The Belgium international scored one goal in 37 league appearances for Cagliari last season.

Nainggolan moved to Cagliari two years ago from Piacenza and is under contract with the Sardinian outfit until June 2014.