TRENTON - State prosecutors released more information Thursday about a large-scale sting involving premium alcoholic beverages dubbed "Operation Swill."

The yearlong investigation alleges that 29 bars and restaurants in the state were putting house or inexpensive alcohol into premium liquor bottles, serving it to customers and charging the premium price.

The New Jersey Division of Alcoholic Beverage Control (ABC) and the Division of Criminal Justice took samples of various alcoholic beverages, as well as records, from those establishments.

In at least one instance, a bar is accused of mixing food dye with rubbing alcohol and serving it as scotch.

The ABC says it seized 1,000 open premium brand name bottles of vodka, tequila, rum and other liquors on Wednesday. Those bottles will be tested by the ABC, as well as the manufacturers.

More than 100 investigators participated in the action, which was the result of customer complaints and tips, according to Attorney General Jeffrey Chiesa. Samples of drinks served "neat," or without ice or mixers, were taken by detectives from each bar or restaurant and tested.

Chiesa says each establishment will have seven days to provide the ABC with premium brand sales records, as well as information about the employees that were working on the days the samples were taken.

Among those included in the sting were 13 TGI Friday's restaurants owned by Livingston-based Briad Group.

In a statement, TGI Friday's said the company has just been made aware of the issue and is working with franchisees and owners to investigate the allegations.