US prosecutors have accused Brisbane man Peter Phillip Nash of being one of the central figures in the hidden, encrypted internet "black-market bazaar" Silk Road.

It is alleged the Silk Road website was used by several thousand drug dealers to distribute hundreds of kilograms of heroin, cocaine, LSD and other illegal drugs and illicit goods to more than 100,000 buyers around the world over the past two and a half years.

Nash, 40, was employed since January 2013 by Silk Road's San Francisco-based owner Ross William Ulbricht, known by the alias Dread Pirate Roberts, as the primary moderator of the website's discussion forums, prosecutors said.

Nash, who went by the aliases "Batman73" and "Anonymousasshit", was named in an indictment unsealed on Friday by prosecutors in New York.

He was arrested in Brisbane by Australian Federal Police on Friday and faces extradition to the US.

Two other alleged Silk Road employees, Andrew Michael Jones, 24, of Virginia, and Gary Davis, of Ireland, were also named in the indictment.

Ulbricht paid the site administrators and forum moderators salaries ranging from about $US50,000 ($A56,600) to $US75,000 a year for monitoring user activity on the website, responding to customer inquiries and resolving disputes between buyers and vendors, it is alleged.

The three men are charged with one count of money laundering conspiracy, which carries a maximum sentence of 20 years in US federal prison.

They are also charged with narcotics conspiracy and conspiracy to commit computer hacking.

Ulbricht was arrested in San Francisco on 1 October.

Preet Bharara, the US attorney for the southern district of New York, praised the help of the Australian Federal Police with the investigation into Nash.