Koulibaly, previously a target of Premier League champions and Arsenal's rivals Chelsea, was superb for Napoli last season, and has earned the nickname ‘The Wall’ among fans for his defensive steel and composure.
The former Genk defender caught the eye of a number of Europe’s top clubs last season, after his performances powered Napoli to a third-placed finish in Serie A, just one point behind runners up Roma.
Chelsea were consistently linked with lucrative moves for the 26-year-old last season, and Napoli apparently rejected a whopping £52m bid from the Premier League champions in in the summer of 2016.
However, fresh from their £52m club-record capture of Alexandre Lacazette, Arsenal have now expressed their interest in the defender, according to TuttoMercatoWeb, and had an approach for the Senegal international rejected, with Napoli extremely reluctant to lose their defensive leader.
Gunners boss Arsene Wenger is known to be keen to bring in experienced defensive options, as he plans to continue with a three at the back system next season and has already added Schalke full back Sead Kolasinac to the squad on a free deal.
While Napoli won't want to lose an important figure like Koulibaly - whose current contract with runs until June 2021. However, the Premier League's insatiable summer spending means they may yet receive an offer they can’t refuse.