An Australian entrepreneur who claimed to be the inventor of bitcoin has backed out of his promise to provide "proof" of his claim. In a blog post published Tuesday, Dr. Craig Wright said he would transfer some early bitcoins from "block 9" by using a private key only known to the cryptocurrency's elusive creator, Satoshi Nakamoto, following widespread skepticism.

However, Wright deleted his website Thursday, writing in an apology letter that he would stay away from the spotlight.

"I believed that I could put years of anonymity and hiding behind me. But, as the events of this week unfolded and I prepared to publish the proof of access to the earliest keys, I broke. I do not have the courage. I cannot," he wrote.

On Monday, Wright provided what he called "extraordinary proof" of a digitally-signed transaction that would prove he controlled Satoshi's key. However, this was debunked by security researchers, according to the BBC. Members of the bitcoin community accused Wright of hoaxing after documents were leaked to Wired and Gizmodo, prompting an investigation into Wright's claim to be the tech's creator.

"When the rumors began, my qualifications and character were attacked. When those allegations were proven false, new allegations have already begun. I know now that I am not strong enough for this," he said.

Wright apologized to Jon Matonis, a former board member of the Bitcoin Foundation, and Gavin Andresen, one of the first programmers of Bitcoin.

"I know that this weakness will cause great damage to those who have supported me, and particularly to Jon Matonis and Gavin Andresen. They were not deceived, but I know that the world will never believe that now. I can only say I'm sorry. And goodbye," Wright said.

Matonis and Andresen have supported the Australian businessman's claims after the two were privately shown additional evidence. In an interview with Wired on the latest revelations, Andresen described the process Wright used to convince him, telling the magazine that he's "still convinced he's Satoshi despite the really weird proof he's put in his blog post." While Andresen believes Wright is the creator of bitcoin, he admitted that "it's certainly possible I was bamboozled."

Matonis took to Twitter also backing Wright's claim.