NEW YORK (AFP) - The creator of shadowy online marketplace Silk Road faces a lengthy prison sentence after a New York jury convicted him of masterminding the criminal website dubbed the "e-Bay of drugs."

Ross Ulbricht, 30, was shown to have amassed a fortune of US$18 million (S$24 million) from the underground Internet bazaar which provided a platform for more than one million drug deals in nearly three years.

The unanimous verdict was returned after just a few hours of deliberations at the end of a trial considered a landmark case in the murky world of online crime and government surveillance.

Ulbricht, who was arrested in October 2013, had pleaded not guilty to seven charges of narcotics trafficking, criminal enterprise, computer hacking and money laundering.

"The supposed anonymity of the dark web is not a protective shield from arrest and prosecution," said Manhattan attorney Preet Bharara.

"Ulbricht's arrest and conviction - and our seizure of millions of dollars of Silk Road bitcoins - should send a clear message to anyone else attempting to operate an online criminal enterprise."

Defence lawyer Joshua Dratel admitted that Ulbricht had dreamt up the website, but insisted it was only an "experiment" and that the real criminal mastermind was someone else.

But the jury decided that Ulbricht was indeed "Dread Pirate Roberts" - the online alias of the Silk Road operator.

The government brought overwhelming evidence against him after his arrest, red-handed, with a laptop of incriminating evidence in a San Francisco library.

The government said 95 per cent of the products on Silk Road were drugs, with the rest fake IDs, hacking tools and hacking services.

It said Ulbricht made buying heroin, cocaine and crystal meth as easy as online shopping from eBay and Amazon until the Federal Bureau of Investigation shut it down.

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

Family and friends have been convinced of Ulbricht's innocence, setting up a "Free Ross" website that raised US$339,000 for his defence.

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.