Los Angeles (CNN) -- Customs agents in Los Angeles seized 20,457 pairs of fake Christian Louboutin shoes shipped from China, U.S. officials said Thursday.

The counterfeit lacquered "red sole" shoes, an icon in women's fashion, could have brought $18 million if they had reached the online and underworld market, according to U.S. Customs and Border Protection officials.
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"CBP maintains an aggressive and proactive posture on intercepting shipments containing counterfeit and pirated items," CBP Director of Field Operations in Los Angeles Todd C. Owen said.

Five shipments were seized at the Los Angeles/Long Beach seaport on July 27 and August 14, the CPB release said.

"Often available on illegitimate websites and underground outlets, counterfeit high fashion commodities multiply the illegal profits of smugglers and traffickers," the agency said. "The public is misguided into believing they are buying an original product at a significant discount."