Ross Ulbricht is pleading not guilty to charges that he is the "Dread Pirate Roberts", the mastermind behind the online drugs emporium Silk Road.

"Not guilty", Ulbricht replied to each of the charges of narcotics trafficking, conspiracy, computer hacking, and money laundering read out to him as he was arraigned in Manhattan federal court.

Prosecutors allege that using the pseudonym taken from the film The Princess Bride, he built the "eBay of the drug trade", the $1.2 billion drugs market Silk Road.

They described the site as "the most sophisticated and extensive criminal marketplace on the internet today", and told judge Katherine Forrest that extensive evidence, including information taken from Ulbricht's own computers and documents, showed that he was behind the operation.

Ulbricht's lawyer, Joshua Dratel, said he plans to file motions challenging his client's indictment.

After prosecutors alleged that he paid $730,000 to have six people murdered, the former post-graduate student of solar cells was denied bail.

Forrest set a 3 November date for the trial.