Whole Foods supermarkets have been routinely overcharging customers by overstating the weight of prepackaged meat, dairy and baked goods, New York's consumer chief said Wednesday.

The price on a package of coconut shrimp at the upscale market was too high by $14.84 (U.S.), said Department of Consumer Affairs commissioner Julie Menin. A package of chicken tenders was overpriced by $4.85, and a vegetable platter by $6.15, the department said.

"These overcharges are incredibly troubling," Ms. Menin said, alleging they continued even after Whole Foods was informed of the city investigation, which began in the fall. The investigation checked the eight Whole Foods markets then open in the city. A ninth has since opened. In all, the Austin, Tex.-based chain has 422 stores in the United States, Canada and Britain.

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"We have been meeting with Whole Foods for months," the commissioner said, "but we repeatedly found problems that were incredibly pervasive."

In e-mailed statements, Whole Foods said, "We disagree with the DCA's overreaching allegations." It said the department had made "grossly excessive monetary demands" to settle the dispute, but it would not disclose the amount.

Because the city's investigation of Whole Foods is ongoing, penalties have not yet been assessed, Ms. Menin said. Fines for falsely labelling a package can be as much as $950 for the first violation and up to $1,700 for subsequent violations. The department said Whole Foods had thousands of potential violations.

Last year, Whole Foods agreed to pay $800,000 in penalties – and improve pricing accuracy – after an investigation into alleged pricing irregularities in California.

The Consumer Affairs Department said it tested 80 different types of prepackaged products and found mislabelled weights for each, with overcharges ranging from 80 cents for a package of pecan panko to the $14.84 markup on the shrimp.