TRENTON - A yearlong investigation into the alleged substitution of premium liquors with non-premium brands has resulted in the seizure of inventory from 29 licensed bars and restaurants.

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 as part of what investigators are calling "Operation Swill."

Authorities say the bars and restaurants named in the investigation were filling premium brand bottles with the non-premium brands and serving them to customers.

The ABC says the customers would then be ordering and paying for "top-shelf" liquors and receiving the non-premium beverage.

More than 100 investigators participated in the action, which was the result of customer complaints and tips. Samples were taken by detectives from each bar or restaurant and tested.

Among those included in the sting were 13 TGI Friday's restaurants.

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.

The state attorney has planned a news conference for Thursday to discuss more about what led to the investigation.