Off-duty police officers had their Christmas celebrations cut short when the boat they were partying on was found to be operating illegally.

The off-duty officers, understood to be from a suburban police station, were partying on a boat cruising the Yarra River near Docklands on Friday when it was stopped by Water Police for a routine check.

It was soon discovered that the party boat was operating without the correct liquor licensing.

It later became apparent the boat was full of off-duty police officers, making the inspection rather awkward.

Police confirmed a number of boats in Docklands were inspected by officers from the Divisional Licensing Unit on Friday "as part of an ongoing operation".