Manchester United have tabled a bid for Napoli defender Kalidou Koulibaly.

Gazzetta dello Sport via Sport-Express says Napoli have rejected United's opening offer for Koulibaly.

The English giants offered €30m for the 30-year-old Senegal international, which was immediately turned down by the Neapolitans.

Napoli are open to doing business for Koulibaly, though the Italian club is demanding at least €50m for their defender. It's been suggested United made their move for the stopper as an alternative to Real Madrid centre-half Raphael Varane, who remains their top defensive transfer target for the summer market.

Koulibaly has a contract with Napoli to 2023. He moved to Napoli from Genk in 2014 for almost €8m. Born in Saint-Dié-des-Vosges, Koulibaly was capped at U20 level by France before committing his international future to Senegal. He now boasts 47 caps.

Last season he made 37 appearances in all competitions for Napoli.

- updated July 21