The US has formally accused North Korea of forging millions of dollars of high-quality counterfeit US dollar notes, known as supernotes.
Sean Garland is accused of handling the counterfeits
A US court indictment said seven men, including senior Irish republican Sean Garland, distributed the $100 fakes.
North Korea has long been suspected of making supernotes, but this was the first time the US has given details.
The US is seeking the extradition from the UK of Mr Garland, who denies the charges against him.
According to a statement from the US Justice Department, the indictment "describes the efforts of Garland and certain of his associates, between December 1997 and July 2000, to obtain quantities of the counterfeit notes from North Korean sources and to transport, and to either pass as genuine or resell, the Supernotes in the United Kingdom and elsewhere".
The statement said that the "highly deceptive notes - which began to appear in worldwide circulation in or about 1989 - were manufactured in the Democratic People's Republic of Korea [North Korea] and under auspices of the government and transported worldwide by North Korean individuals acting as ostensible government officials".
Mr Garland is accused of handling up to $1m of the supernotes, and of pretending to co-conspirators that the source was Russia, the statement said.
The other men charged in the indictment are Christopher John Corcoran, 57, of Dublin, Ireland; David Levin, also known as David Batikovitch Batikian, 39, of Birmingham and London; Hugh Todd, 68, of South Africa; and Terence "Terry" Silcock, 50, Mark Adderley, 47, and Alan Jones, 48, of Birmingham, United Kingdom.
North Korean trafficking
The indictment comes in the context of a wider US campaign against North Korean contraband.
The US accused the North, in a State Department report last year, of state-sponsored drugs trafficking.
It cited the 2003 apprehension of a North Korean ship in Australian waters allegedly carrying up to 125kg (275 pounds) of heroin and allegations by defectors that North Korea was engaged in large-scale opium poppy production.
And last month, the US accused a bank in Macau of laundering money for the impoverished state.
It is believed that the North engages in such illicit activities in order to earn hard currency to shore up its embattled economy.
Mr Garland is the president of the Irish Workers' Party, the political wing of the Official Irish Republican Army (IRA).