A number of Italian clubs want the 33-year-old defender, but Napoli are particularly eager to sign the Belgian.
Vertonghen would be a low-cost and experienced replacement, commanding no transfer fee.
Raffaele Auriemma of Tuttosport says Napoli sporting director Cristiano Giuntoli has contacted Vertonghen’s agent.
Napoli have proposed a two-year contract with the option of a third, an interesting offer considering the player’s age.
The Partenopei hope this offer will be enough to see off strong competition for Vertonghen.