A top Treasury Department official said Friday the United States has been urging financial institutions throughout the world to consider terminating all business dealings with North Korea. Undersecretary of the Treasury Stuart Levey said the line between North Korea's licit and illicit money is nearly invisible. "The US government is urging financial institutions around the world to think carefully about the risks of doing any North Korea-related business," said Levey, who deals with terrorism issues and financial intelligence. In a speech prepared for delivery to the American Enterprise Institute, Levey also took aim at Banco Delta Asia (BDA), a Macau-based bank that he said was "handling North Korea's dirty business without any pretense of due diligence or control. "BDA was a willing partner, actively helping North Korean agents conduct surreptitious, multimillion dollar cash deposits and withdrawals without questioning the basis of these transactions," he said. The United States has designated the bank as being of "primary money laundering concern" and cut off its access to the US financial system. It also imposed sanctions against North Korea on grounds that it counterfeited US dollars and engaged in other acts of financial wrongdoing. North Korea has since boycotted six-party nuclear disarmament talks and says resumption of the discussions will not be possible until the sanctions are lifted. Levey said a number of foreign jurisdictions and institutions have suspended financial dealings with North Korea in the wake of the US actions, a trend that he said has accelerated since the country caused an international stir last July by testing seven ballistic missiles. Institutions in China, Japan, Vietnam, Mongolia and Singapore have curbed business ties with North Korea, he said. "It is becoming very difficult for the Kim Jong-Il regime to benefit from its criminal conduct," Levey added.