CHICAGO – The U.S. Food and Drug Administration said Tuesday that it is reviewing the results of a multi-state investigation that found that shoppers have been paying for large amounts of ice that are not supposed to be included in the price of frozen seafood.

The investigation — conducted by weights and measures inspectors in 17 states, including Maine — found that a coating of ice applied to frozen seafood to preserve quality during storage and distribution was often wrongly included as part of the labeled weight of seafood. In some instances, the investigation found, ice accounted for up to 40 percent of the product’s weight.

“We’re reviewing their results and determining whether FDA should take any action, and if so, what actions should we take,” said the FDA’s Michael Herndon.

If the FDA determines that economic fraud is taking place, he said, they first issue a warning letter and later take “stronger action” if necessary. Herndon said the FDA has issued numerous warning letters on the seafood issue.

More than 21,000 packages of seafood were removed from store shelves and distribution centers during the four-week investigation. A “significant market share” of packers were not following the law, either knowingly or because they didn’t realize that they weren’t supposed to include the weight of the ice glazing.

In some cases, investigators found seafood packers were also adding a thicker coat of ice than necessary in order to add weight to the seafood.