The report claims that four Serie A clubs are also looking to sign the 86-times capped Belgium international in January. Spurs and Arsenal are also vying for his signature.
The Naples club are going through a crisis at the moment and several top players including Mertens and Jose Callejon could be sold by the club.
Both the Milan clubs, Juventus and Roma are interested in signing Mertens who has scored an impressive 88 goals and provided 47 assists in 216 appearances for them in Serie A since joining from PSV in 2013.
Spurs and Arsenal have reportedly opened talks with the Belgian’s entourage over a January switch to north London.
Mertens is a very good player, but doubts remain about whether Spurs would spend the money on a 32-year-old forward, even if he is available on the cheap.
Furthermore, Spurs have enough depth and quality in their attacking midfield or forward areas, and they must focus on bolstering their defence instead.
Mertens could be a smart signing for the Gunners. A player of his calibre could give them the lift they need to make a serious challenge for the top four positions.