U.S. Immigration and Customs Enforcement Director John Morton said authorities also have shut down more than 300 websites selling counterfeit goods as part of an enforcement effort dubbed "Operation Red Zone."
The operation targeted international shipments of jerseys, hats and other souvenirs entering the U.S. for sale by stores, flea markets and street vendors.
More than 160,000 counterfeit items, mostly purporting to be official Super Bowl and other NFL merchandise, were seized during the operation. A total of 23 people have been arrested on related charges since September 2012.
"We attacked the counterfeiters at every point along the criminal supply chain," Morton said during a press briefing in New Orleans.
Morton said agents also were in the city this week to crack down on the sale of counterfeit merchandise before Sunday's Super Bowl between the San Francisco 49ers and Baltimore Ravens.
"This just takes good old-fashioned police work, people getting out on the streets," he said.
This is the fifth consecutive year that federal authorities have launched a similar operation to crack down on the sale of counterfeit sports goods. Roughly $5.1 million in goods were seized during the previous one, Morton said.
"This is the largest number we've ever seized," Morton said of the $13.6 million.
Morton said copycat websites selling bogus merchandise have become increasingly sophisticated in their efforts to dupe customers into believing they're purchasing licensed, official sportswear.
"The prices are not ridiculously low. They're just discounted enough to fool the consumer," he added.
Anastasia Danias, the NFL's vice president for legal affairs, said fans also need to be wary of buying counterfeit Super Bowl tickets from "any suspicious sources."
"We learn of hundreds of fans every year who travel to the host city with the hope of watching their team play in the Super Bowl game only to be turned away at the gate, having bought counterfeit tickets or tickets that were reported lost or stolen," she said.
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