Arsenal captain Laurent Koscielny's refusal to travel with the rest of the team is due to the club's unwillingness to honour a request to have his contract cancelled, according to reports.
The club confirmed that the French international had refused to board the plane to the United States of America with the rest of the team on Thursday morning.
It is believed that the 33-year-old wants to leave the club ahead of next season, and had requested the club to release him from their agreement.
Koscielny's contracts runs until next year, and the club has refused to grant the former Lorient man his wishes.
The club said they will begin investigations into the whole saga, with internal disciplinary proceedings also set to be meted on him.
"We are very disappointed by Laurent’s actions, which are against our clear instructions. We hope to resolve this matter and will not be providing any further comment at this time," read part of the statement.
If the club fails to reach an agreement with the captain, they will be forced to look elsewhere for a new defender, even as reports indicate their budget for the summer is seriously lean.
They (Arsenal) are said to be close to capturing William Saliba from St. Etienne, even though he might be loaned back for a season.
Koscielny has made 353 appearances for Arsenal since joining from Lorient in 2010, scoring 27 goals and winning two FA Cups.