Koumas had been given extra time off after a dental operation and was due back on Tuesday.
A meeting had been set up for Monday to have "clear the air" talks with training to resume on Tuesday but Koumas, according to the WBA website, asked for that meeting to be moved to the Tuesday.
The club say they agreed but on Tuesday Koumas did not show up for the meeting or for training and left his agent to conduct talks on his behalf.
The club say they had no alternative other than to take disciplinary action. Koumas has been been given until Monday to appear otherwise further action will be taken.
Koumas himself told the Western Mail that he has had meetings with the Chairman. His position at the club must be unstable with disciplinary action taken against him.