NEW ORLEANS (AP) — Investigators have confiscated more than $13.6 million worth of phony sports merchandise over the past five months and expect to seize more in New Orleans during Super Bowl week, a federal law-enforcement official said Thursday.

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.

And federal investigators say they have intelligence that shows even the Mexican drug cartels are getting involved in the counterfeit NFL black market trade because they can make quick money by selling fake jerseys in flea markets and parking lots.

In September, for example, HSI's newly created trade enforcement unit seized dozens of counterfeit San Francisco 49ers, Minnesota Vikings and Miami Dolphins jerseys around New Mexico. Agents have also raided flea markets in El Paso, Texas, and seized NFL jerseys that federal agents say were believed to be linked to cartels in northern Mexico and local gangs like Barrio Azteca.

Officials say that a number of seizures of fake NFL materials have shown evidence that cartels are venturing into the lucrative black market in border states, although they are just finding out how the operations work. Federal agents believe cartels are using the counterfeit trade to launder money and expand their illegal activities as authorities step up drug enforcement.

'Cartels are seeking to get their hands into any illegal activity they can,' said Kevin Abar, assistant special agent in charge of Homeland Security Investigations in New Mexico. 'A lot of folks may think that there's nothing wrong with buying a knockoff Denver Broncos jersey, but in reality, the money is being used to fund the drug war in Mexico.'

More than 160,000 counterfeit items, mostly purporting to be official Super Bowl and other NFL merchandise, were seized during 'Operation Red Zone.' 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.

Andy Hageman, owner of House of Football, an Albuquerque store that sells authentic, licensed NFL products, said every week he gets customers who find out that they had purchased fake jerseys online or at other stores. 'They ask me to see if the shirt is a fake, and I usually can tell right away,' said Hageman.

The quality counterfeit jerseys also vary, federal officials say. Authentic jerseys can usually be identified by the required NFL hologram logo and the high quality stitching, officials said.

'Sometimes, you can't even tell they are fakes,' said Abar. 'Other time, the jerseys have 'Patriots' misspelled.'

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.