A new U.S. Treasury report estimates that more than half of the $760 billion of U.S. currency in circulation is held abroad. The popularity of U.S. currency makes the banknotes a target for many counterfeiters.
U.S. State Department spokesman Sean McCormack has expressed concerns about the existence of counterfeit American currency abroad raised in a recent U.S. Treasury report.
He said North Korea's activities in this field have caught attention.
"We very clearly have been quite concerned about North Korea's illicit activities, including counterfeiting of U.S. currency," he said. "And the United States is going to continue actions it deems appropriate to protect itself in this regard to protect its currency. This is a very basic function of government - protecting its own currency. We think that every state around the world would take steps to do so."
The report accuses the North Korean government of authorizing and controlling the production of highly deceptive counterfeit notes - so called "supernotes."
The U.S. Secret Service first detected these fake bills in 1989. The report says that nearly 22 million of these North Korean "supernotes" have gone into circulation since then. However, the report says that during the course of the 16-year investigation, U.S. agents have seized approximately $50 million worth of the counterfeit currency.
McCormack says the United States will continue to investigate North Korea's involvement with this highly advanced form of counterfeiting.
Last year, the U.S. government cut off all financial transactions with a Chinese bank in Macau. U.S. authorities determined the bank was helping to distribute North Korean "supernotes".
Special Agent Bill Sims, who heads the Secret Service field office in Miami, Florida, said that in March 2005, his office investigated the appearance of a large quantity of these highly deceptive notes and determined the bills had passed through Peru.
Sims says foreign governments have helped his agency's efforts to clamp down these illegal activities.
"There is an interest by a lot of our foreign partners to assist because a lot of this equipment can be used to produce not only counterfeit currency but also counterfeit identification as well as counterfeit currency from other countries, so there is a very heightened sense of awareness," he said.
In June of this year, Interpol repeated its warning on North Korea's efforts to purchase printing supplies that would help in counterfeiting U.S. currency.
However, the U.S. Treasury maintains that counterfeiting of U.S. dollars remains low abroad.