Napoli have confirmed that striker Romelu Lukaku failed to report for training on Tuesday, prompting the Serie A champions to consider disciplinary measures against the Belgian international.
The club released a statement announcing the forward's absence from their training ground following the international break.
"Napoli announce that Romelu Lukaku did not respond to today's call-up ahead of the resumption of training," the club declared.
"The club reserves the right to evaluate the adoption of appropriate disciplinary measures as well as the continuation of the player's participation in the team on an indefinite basis."
Romelu Lukaku withdrew from Belgium's squad last week but has stayed in Belgium
|PA
The 32-year-old's immediate future at the Italian club now hangs in the balance.
Lukaku withdrew from Belgium's squad last week ahead of World Cup warm-up fixtures against the United States and Mexico, citing fitness concerns.
Rather than returning to Naples for rehabilitation, the former Chelsea and Manchester United striker opted to remain in his home country to train on his own.
Italian media reported that the 32-year-old declined to travel back to the club's training facilities despite being summoned.
Romelu Lukaku won the Serie A last season with Napoli | GETTYThe decision to stay in Belgium without the club's authorisation has escalated tensions between player and club during what has been a troubled campaign for the forward.
Lukaku took to social media on Monday to defend his decision, revealing the physical and emotional struggles that have plagued his season.
"The truth is the last few weeks I wasn't feeling right physically and I had it checked out while I was in Belgium and it showed me that there was an inflammation and liquid on my hip flexor muscle next to my scar tissue," the striker explained.
He noted this marked his second setback since returning from a hamstring injury in early November.
The Belgian also acknowledged the mental burden of a difficult year, which included the death of his father Roger last September at the age of 58.
"I could never turn my back on Napoli, never," Lukaku insisted.
Romelu Lukaku has struggled this season amid injuries, managing just seven appearances in all competitions
| GETTYThe club's legal team is currently scrutinising the situation, with reports suggesting the response could extend beyond mere exclusion from the squad.
According to Sky Sport, Napoli's lawyers are examining all available options under the terms of Lukaku's contract, including the possibility of terminating his agreement with the club entirely.
The striker has endured a frustrating campaign, managing just seven appearances and a single league goal in five substitute outings since his January return from injury.
Napoli currently sit third in Serie A, trailing leaders Inter Milan by seven points, and face second-placed AC Milan at the Stadio Maradona on Monday.