Aberdeen have confirmed that wantaway forward Duk will now face disciplinary proceedings after failing to turn up to training.
The club say they have made a number of attempts to communicate with the 24-year-old without reply.
A club spokesperson said: "Duk has failed to report to training and is currently absent without permission.
"The club has made attempts to communicate with Duk but he has refused to engage with us directly.
"He is now subject to internal disciplinary proceedings.
"We're naturally disappointed with the situation but can't say anything further at this stage."
At a press conference on Friday, Aberdeen head coach Jimmy Thelin revealed Duk would not be in the squad to face Queen of the South on Saturday in the League Cup due to "internal issues".
