DETROIT (WWJ) – More than $4 million in counterfeit cash was confiscated by U.S. Customs and Border protection at Detroit Metro Airport.

The seizure was made Friday after a Vietnamese couple arrived in metro Detroit on a flight from Seoul, Korea.

Customs agents say the married couple was referred for a baggage examination because they made conflicting statements about carrying more than $10,000 in cash.

A secondary search of their luggage resulted in a large discovery of what agents call “hell money” — a form of joss paper printed to resemble legal tender. The notes are not an officially recognized currency nor are they legal tender.

Agents said the couple was carrying 93 bundles of counterfeit U.S. $100 bills and 32 bundles of counterfeit Vietnamese Dong, the national currency of Vietnam. The couple allegedly told agents the money was to be burned as an offering to a dead relative, as often practiced in certain Asian cultures

“Attempting to import any amount of counterfeit currency, regardless of the intended purpose, can have serious implications for arriving travelers,” Devin Chamberlain, Port Director, said in a statement. “Quality law enforcement work and solid attention to detail resulted in this seizure, and I am proud of the officers involved.”

Agents from Homeland Security Investigations and the U.S. Secret Service responded to the airport and took custody of the currency.

Agents are reminding all travelers that the manufacturing of, and/or importation of counterfeit bank notes could result in federal charges.