Calum Chambers's £16m move from Southampton to Arsenal is to be investigated by the Football Association, following an alleged complaint by a third party.
The FA is refusing to say what the probe is about, and there were no known issues between the Saints and the Gunners during or after the deal was made.
According to the Daily Mail, former teammates suggest the issue lies with Arsenal. However, the club's spokesperson told the newspaper: "Everything was open, cordial and above board with Southampton throughout the Calum Chambers transfer."
The FA will also reportedly not comment about the issue, leaving both clubs confused about the investigation.
