Law-enforcement officials are warning Hawai'i residents to check their wallets for counterfeit currency, as nearly $20,000 in fake $100 bills have turned up in the past two weeks throughout the state.

The bills originated in Los Angeles, where they were produced and circulated by two street gangs, the Bloods and the Crips, said Albert Joaquin, special agent-in-charge for the U.S. Secret Service office in Honolulu.

The quality of the printing on the bills is very good, Joaquin said, as they were manufactured by a high-quality copy machine that can cost up to $100,000. Counterfeiters have treated the bills with a chemical that can fool pens some merchants use to detect fakes.

The bills were discovered in Macy's at Pearlridge Center and other shopping centers on O'ahu and on the Neighbor Islands. They have turned up in other businesses as well, "from fast-food places to high-end stores," Joaquin said.

The Secret Service is asking residents who think they may have fake notes to take them to a bank, which can verify whether a bill is real or counterfeit.

The Honolulu Police Department is asking that merchants be on the lookout for counterfeits and to call HPD with information about the origin of the fakes or if someone tries to use them.

Genuine $100 bills have a watermark with Benjamin Franklin's image to the right of the central portrait.

For more information on how to detect counterfeit bills, go to www.secretservice.gov/know_your_money.shtml.