Napoli have reportedly rebuffed a record bid from Chelsea for Senegalese defender Kalidou Koulibaly as the Serie A giants are not in a mood to sell their prized asset.

Koulibaly, 25, has been the prime target for Antonio Konte since he took over the reigns at Stamford Bridge.

Gazzetta dello Sport says the Blues had lodged a fresh £50.2m offer for the player in a bid to test Napoli’s resolve.

However, the Italian club have swiftly turned down the approach as they are unwilling to lose their asset just days before the transfer deadline.

Maurizio Sarri’s side have previously offloaded Gonzalo Higuain to Juventus for a £75.3m fee, and this has urged the club to keep hold of Koulibaly’s services.

The Blues are likely to make a renewed attempt to sign the defender with Conte desperate to get his hands on a top-class centre-back.

Conte is keen to strengthen his central defensive options before the window slams shut with just veteran skipper John Terry, Gary Cahill and the crocked Kurt Zouma in his squad.

Chelsea opened their Premier League campaign with a win over West Ham and the Italian boss is keeping one eye on the transfer market.

The 25-year-old Napoli defender was impressive for the Serie A giants throughout last season, making 33 appearances as his team finished runners-up to Juventus.

And his exciting form apparently caught the eye of new Chelsea boss Antonio Conte, with the Italian making the Senegal international his top priority target this summer as he is keen to overhaul his new squad following their unexpected 10th place Premier league finish last term.

Conte needs a new defender with just Kurt Zouma, Gary Cahill and John Terry his only first-team options at the back. Skipper Terry, 35, is expected to play a reduced role this season, while Zouma is recovering from a knee injury. Right-back Branislav Ivanovic could cover the central positions until a permanent arrival is sorted.