Manchester United receive boost in pursuit of Serie A star
The Senegal international has enjoyed another excellent season at the Stadio San Paolo, with the Partenopei set to finish in the top two in Serie A for the third time in the last four seasons.
Koulibaly, who is regarded as one of the best centre-backs in Europe, has been heavily linked with Manchester United in recent weeks.
And although Ancelotti insists Napoli do not need to sell their star players this summer, he says he will not block the departure of anyone who wants to seek pastures new.
"We don't need to sell our best players," the Italian said. "We can sign new players following our ideas.
"However, I am not going to block whoever wants to leave. I've never done it in my career."
United have apparently identified Koulibaly as one of their leading targets as Ole Gunnar Solskjaer seeks to bolster his defensive options ahead of next term.