Dries Mertens has signed a new contract with Napoli until 2020, the club have announced.
Mertens, 30, has been Napoli's star player this season with 27 goals and nine assists in 34 Serie A appearances.
The Belgium international's form has led to speculation about a move away with Inter Milan and Manchester United reportedly interested.
- Official SSC Napoli (@en_sscnapoli) May 27, 2017
"We were together from 2.30 p.m. in the afternoon to 1.40 a.m. in the morning, including our lawyer, the lawyers from Belgium, his Milanese consultants, financial experts on the phone and after hours of technical discussion, we all worked out a perfect bilateral agreement for Dries and Napoli."
Napoli lost Gonzalo Higuain to Juventus last summer when the Bianconeri met the striker's release clause, and although De Laurentiis confirmed Mertens has a similar clause in his new deal it will only be valid for clubs in China.
"It protects the fans and me," De Laurentiis added. "Dries will stay with us for a few more years, unless of course he wants to go to China and next year someone pays the release clause that he wanted introduced and I cannot refuse.
"I was not in favour of the release clause after the Gonzalo Higuain mistake, but we learned from it, so there is a release clause on Dries' contract that is valid only for China.
"Relax, Mr Mertens will only play for Napoli in Italy. If he is to leave, it'll be for outside of Italy."
Napoli face Sampdoria on Sunday in their final game of the season and if they better Roma's result they can finish second in Serie A and qualify automatically for the Champions League.
They are guaranteed to finish third and at the least a place in the qualifying rounds for the Champions League.