Federal authorities say they seized more than $4.6 million in counterfeit U.S. currency at Detroit Metropolitan Airport from a couple traveling into the country from Vietnam.

U.S. Customs and Border Protection says that its officers on Friday seized seversl bags from a married Vietnamese couple after they arrived at the airport in Romulus on a flight from Seoul Korea.

Officers found 93 bundles of counterfeit $100 bills and 32 bundles of Vietnamese currency that the agency says were intended to be burned as part of an offering to a deceased individual in a cultural ceremony.

Federal officials say it’s illegal to import counterfeit currency, regardless of the intended purpose.