Napoli have confirmed Romelu Lukaku did not respond to their call asking the striker to return to training on Tuesday.
Lukaku was initially called up to the Belgium national team before he left the squad due to his fitness problems.
However, the 32-year-old decided to stay and train in Belgium, and has now ignored the club's request for him to return to Naples.
After suffering an injury in the final stages of pre-season, Lukaku has played just 64 minutes this term from a total of seven appearances.
Napoli have now announced they will consider taking disciplinary actions against Lukaku, who may also be told to train separately from the team.
The club released a statement that read: "SSC Napoli can confirm that Romelu Lukaku did not respond to today’s call to return to training.
Nota del Club https://t.co/BjQ8433Wik
— Official SSC Napoli (@sscnapoli) March 31, 2026
"The club reserves the right to consider taking the appropriate disciplinary action, as well as to determine whether the player will continue to train with the team for an indefinite period."
Antonio Conte's side have won each of their last four games in Serie A, seeing them move within seven points of leaders Inter with eight games to go.
They host title rivals AC Milan in their first match after the international break, with the Rossoneri one point above Napoli.