'Bitcoin creator' denies involvement
The man named by a magazine as the inventor of Bitcoin earlier this week has denied any involvement.
Dorian Prentice Satoshi Nakamoto said he had not even heard of the virtual currency until a few weeks ago.
Nakamoto was singled out as the man who wrote the code underpinning Bitcoin by Newsweek.
But he said that quotes attributed to him that seemed to suggest his discontinued involvement with the project had been "misunderstood".
"I got nothing to do with it," Nakamoto told a reporter on Thursday.
He was identified as the "face behind Bitcoin" in an article published online this week. A reporter spent about two months investigating the claim and tracking him down.
When the reporter - flanked by two police officers - found the 64-year-old former physicist at his home in California and asked him if he was involved with Bitcoin, he is reported to have said: "I am no longer involved in that and I cannot discuss it."
But he told an Associated Press reporter on Thursday: "I'm saying I'm no longer in engineering, that's it. And even if I was, when we get hired, you have to sign this document, contract, saying you will not reveal anything we divulge during and after employment. So that's what I implied.
"It sounded like I was involved before with Bitcoin and looked like I'm not involved now. That's not what I meant. I want to clarify that," he said.
'Unregulated and unstable'
Nakamoto said he was born in Japan and moved to America in 1959 and that English was not his first language.
The value of Bitcoin has fluctuated as knowledge of and interest in what was until recently a little-known currency has increased. It is used to bypass financial institutions, making it attractive to people who want to trade directly. That has led to a level of adoption by speculative investors and some criminal enterprises.
In 2012, a leaked FBI report showed that the the agency was concerned that Bitcoin could become widely used by criminals.
The report said that the virtual currency was an "increasingly useful tool for various illegal activities beyond the cyber realm".
And, in August the following year, it was announced that the "scale of the risk posed by" Bitcoin was to be investigated by the FBI on behalf of a US Senate committee.
The entity behind it has always been known as "Satoshi Nakamoto", although it is unknown whether or not that is a pseudonym. Nakamoto insisted he had never heard of Gavin Andresen, a leading Bitcoin developer.
The latter told Newsweek he had worked closely with the person or entity known as Satoshi Nakamoto in developing the system, but that they never met in person or spoke on the phone.
Nakamoto told the AP that he would have had the technical ability to come up with Bitcoin. He said: "Capability? Yes, but any programmer could do that."
He also admitted that elements of the Newsweek story were correct. He said that he did once work for a defence contractor.
He added that he also worked on missile systems for the US Navy and Air Force and, consequently, it was necessary to keep many details of his work confidential.
Newsweek writer Leah McGrath Goodman, who spent two months researching the story, told the AP: "I stand completely by my exchange with Mr Nakamoto. There was no confusion whatsoever about the context of our conversation - and his acknowledgment of his involvement in Bitcoin."