Active since 1962 (based on a convention dating from 1956), the Mosel Commission aims and organization are comparable to the Danube and Rhine Commissions. The members of the Mosel Commission are France, Germany and Luxembourg. The seat of the Commission is Trier (Germany).
The Mosel Commission website shows the Commission logotype, a white anchor and three white five-pointed stars plus a few shadowy waves in front of the member states' national flags.
In answer to a question of mine, they confirmed the use of a flag with which I take to be the logotype on their website.