The alleged mastermind of a vast online, global criminal enterprise that sold $US200 million worth of drugs to customers all over the world has gone on trial in New York.

US government prosecutors say 30 year old Ross Ulbricht is a criminal kingpin and online drug boss who amassed a fortune of $US18 million ($A19.48 million) from the dark, secretive Silk Road website that conducted more than one million drug deals in nearly three years.

An Australian, Peter Nash, has also been implicated in the case and has been locked up in a New York jail since December pending his trial.

Overseen by US District Judge Katherine Forrest, Ulbricht’s trial is expected to run four to six weeks, and is considered a landmark case in the shadowy world of online crime and government surveillance.

“This is a case about a dark and secret part of the internet … where people can buy dangerous drugs,” federal prosecutor, Timothy Howard, told the jury on Tuesday.

From January 2011 to October 2013, Ulbricht took a cut of almost $US18 million in online currency Bitcoin through deals in drugs such as heroin, cocaine, and crystal meth through the website, Howard said.

“Ross Ulbricht was the kingpin of this digital, criminal empire,” he said.

The government alleges that Ulbricht alone was “Dread Pirate Roberts” – the online alias of the Silk Road operator – and was caught red handed with a laptop of incriminating evidence in a San Francisco library in October 2013.

Ulbricht has pleaded not guilty to seven charges of narcotics trafficking, criminal enterprise, computer hacking and money laundering.

He faces life in prison if convicted.

Summing up the government’s case, Howard said 95 per cent of the products on Silk Road were drugs, with the rest fake IDs, hacking tools, and hacking services.

He said Ulbricht made buying heroin, cocaine and crystal meth as easy as online shopping from eBay and Amazon until the FBI shut it down, he said.

The government alleges he was willing to resort to violence and solicited six murders for hire to keep the scheme intact, although there is no evidence any killings actually took place.

Ulbricht, Howard said, led a secret life and took care not to arouse suspicion with lavish spending, as he saved for a future in the Caribbean.

Family and friends are convinced of Ulbricht’s innocence, setting up a “Free Ross” website that has raised $US339,000 to help pay for prominent defence lawyer, Joshua Dratel.

Dratel told the jury of 12 men and women, with four alternates, his client was “a young man with a lot of ideas” who came up with the idea of Silk Road “as a completely free wheeling website” or “kind of economic experiment”, but said his involvement stopped there.

After a few months, it became so stressful to operate that he handed it off to others and was only lured back “to take the fall” as the real criminals knew the FBI was closing in, Dratel said.

A second version of Silk Road sprung up just weeks after Ulbricht’s arrest. It was shut down and alleged operator Blake Benthall was charged last November.

“The real Dread Pirate Roberts is out there,” Dratel said, calling on the jury to use their common sense, look at the evidence and determine his client’s innocence.

AFP