The accused mastermind of a $6 billion digital currency system allegedly used as an underworld bank for hackers, identity thieves and drug dealers was held without bail Tuesday in federal court in Manhattan following his weekend extradition from Spain.

Arthur Budovsky, 40, the founder of Liberty Reserve, had been awaiting extradition since prosecutors charged in May 2013 that the company's virtual currency helped cyber criminals, child pornographers and fraudsters anonymously launder their proceeds.

Budovsky, who renounced his U.S. citizenship and operated out of Costa Rica in an attempt to avoid U.S. money laundering laws, pleaded not guilty in a brief hearing before U.S. District Judge Denise Cote. He faces up to 30 years in prison.

Defense lawyer Steven Frankel noted after the hearing that although prosecutors have called Liberty Reserve the "hub" of a multibillion-dollar online black market, two co-defendants have pleaded to merely operating an unlicensed money transmitting business.

"Let's see what happens," Frankel said. "You see a bomb of an indictment, then you see all of them pleading guilty to running an unregistered business."

Cote set trial for next September after prosecutor Andrew Goldstein told her evidence to be turned over to the defense -- known as discovery -- included 26 two-terabyte hard drives. Frankel said he'd been told the size of the hard-drives made it the largest discovery ever in a criminal case. Government sources said it was among the largest they'd seen.

According to last year's indictment, Liberty Reserve, which Budovsky started in Costa Rica in 2006 after his conviction of running a similar enterprise in New York, used a digital currency called "LRs" and kept no paper trail on its customers' sources of funds.

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Prosecutors said that before it was shut down in 2013, Liberty Reserve had more than a million users worldwide, including 200,000 in the United States, and conducted 55 million transactions.

Two former technology managers at Liberty Reserve pleaded guilty to conspiracy to operate an unlicensed money transmitting business in September, and face up to five years in prison. But Azzedine el Amine, described as Budovsky's deputy, faces up to 30 years, and Vladimir Kats, described as a co-founder, faces up to 75 years after each pleaded guilty to money laundering, conspiracy and other charges as well as operating a money transmitting business without a license.