Federal authorities have been cracking down on counterfeit sports merchandise since the start of the Stanley Cup playoffs and are warning vendors who sell apparel with fake trademarks that they will face criminal prosecution.

The Immigration and Customs Enforcement (ICE) agency said that after the playoffs began, agents investigated 14 vendors and seized more than 900 counterfeit hats, T-shirts and jerseys worth $58,450.

Most items seized bore counterfeit NHL trademarks, although investigators also found fake items bearing logos from Major League Baseball, the NFL and NBA, the ICE said.

"Vendors who sell counterfeit goods to unsuspecting sports fans will be held accountable. These vendors sell inferior items tarnishing the reputation of trademark holders like the NHL," said John P. Kelleghan, special agent in charge of the ICE Office of Investigations in Philadelphia.

"Not only do these items hurt the trademark holder, counterfeit goods cost U.S. industries billions of dollars in losses each year. ICE will continue to investigate and prosecute crimes that impact the U.S. economy."

Kelleghan urged consumers to look for the hologram sticker or holographic hang tag and a sewn-in or screen-printed neck label identifying a licensee that has been authorized by the NHL to produce "genuine" or "official" merchandise. He said to shop at legitimate retailers, such as the Official Flyers Team Store and NHL.com, rather than street vendors, flea markets, overseas Web sites or other questionable sources, and to beware of ripped tags or irregular markings on apparel.