Lukaku spent two weeks in Belgium during the international break against the club's wishes, recovering from an injury without the supervision of Napoli's medical staff.
Sporting director Giovanni Manna confirmed the club would take disciplinary action: "Romelu was supposed to go to the national team, but he stayed in Belgium to train against our wishes. We wanted to discuss it here in Naples. It didn't happen, and we're not happy. There will be consequences."
Speaking after Napoli's 4-0 win over Cremonese, Conte was blunt.
"I haven't had the chance to speak to him. I know one of our directors spoke to him and that he came to the training centre. My office was right there, but no one knocked on my door. I was very disappointed about that. I would have expected a greeting, a message, or something."
He added: "In these situations, the coach tries to understand everyone, but no one makes the effort to understand the coach."
Lukaku was instrumental in Napoli's Scudetto triumph in 2024-25, contributing 14 goals and 10 assists. But he has managed just seven appearances this season due to persistent injury and fitness issues. Napoli paid €30 million to sign him permanently from Chelsea in the summer of 2024, and he has a contract until 2027.
Reports from Italy this week suggested Napoli are now working on a contract termination scenario for the end of the season. Lukaku's future at the club appears to be over.