Police are warning there will be booze buses around Flemington race course this afternoon to test motorists leaving the Melbourne Cup.

Police plan to continue breath-testing motorists through the night, with booze buses moving from the track to surrounding areas later in the evening.

Inspector Greg Parr says a number of drink drivers were caught on Saturday on Derby Day.

"Regardless of all the messages we put out for Derby Day, we still managed to catch dome drink drivers," he said.

"And sadly two of the drink drivers we caught were probationary licence holders who shouldn't have had any alcohol at all."