Norwich City have made a bid for Napoli defender Kalidou Koulibaly, sources have told ESPN FC.

Norwich boss Alex Neill has made a new central defender one of his top priorities before the close of the transfer window, and he has identified Koulibaly as one of his top targets.

Southampton have also been credited with an interest in Koulibaly as they look to bolster their centre-back options.

However, Norwich are hoping to steal a march on their Premier League rivals by tabling an offer of £8.7million (€12m) for Koulibaly.

Frenchman Koulibaly joined Napoli from Genk in 2014 and made 37 appearances in all competition for the side last season.

Koulibaly was left out of the Napoli starting XI for last weekend's Serie A opening day defeat to Sassuolo and the club are thought to be willing to sell the 24-year-old for the right price.

Norwich have only made four new signings this summer in the shape of Youssouf Mulumbu, Robbie Brady and Jake Kean arriving on permanent deals and Andre Wisdom coming in on loan.