Napoli have warned they will not allow Kalidou Koulibaly to leave in a cut-price deal, insisting the defender's value has not budged during the coronavirus crisis.

The Senegalese centre-back, who turns 29 later this month, has frequently been linked with a move, including to Premier League duo Manchester United and Liverpool.

Clubs across Europe have been hit by the impact of the pandemic, with the financial toll leading to suggestions it could have a major effect on the transfer market.

Yet Napoli have no intention of allowing players to leave below their full value, and sporting director Cristiano Giuntoli said it will take top dollar to prise away any of the club's stars.

Addressing the future of Koulibaly, Giuntoli told Italian broadcaster Sky Sport 24: "He is a great footballer and the club has the right to ask for the price it wants."

Giuntoli does not buy into the theory that the best players will suddenly be available for lower prices than before COVID-19 hit.

"They say negotiations will change, but in my opinion this is an alibi. I don't think the coronavirus issue can change the price of Koulibaly or other top players," Giuntoli said.

"Certainly, however, we'll come to appreciate the contractual formula such as the loan with an option to buy, which help to postpone the guarantees and ease the balance immediately. Football can adapt quickly."