Counterfeit designer blue jeans are among the biggest growth areas in the booming field of knock-off imports into the United States, officials say.

U.S. customs officials and legal experts say luxury blue jean labels such as True Religion, Joe's Jeans and Antik Denim are seeing big increases in counterfeiting, the Los Angeles Times reported Saturday.

"The counterfeiting problem exists with Rolex watches and high-end jeans because people want the cachet without spending the money," Douglas Masters, a Chicago intellectual property protection attorney, told the newspaper. "The opportunity to make money is greater when there's a much higher profit margin."

Customs officials said they intercepted $18 million worth of counterfeit apparel, including denim, from China alone in 2007, marking a 29 percent increase from 2006.

The Los Angeles ports are a center for counterfeit goods imports, mainly because merchants in and around the city are able to sell $2 billion in knock-offs there each year, the Los Angeles County Economic Development Corp. told the newspaper.