But Canongate, based in Edinburgh, said Assange tried to cancel his contract but did not repay an advance, so it decided to publish the first draft received in March, the BBC said.
In a statement, the publishing firm said: "On 7 June 2011, with 38 publishing houses around the world committed to releasing the book, Julian told us he wanted to cancel his contract. However, he had already signed his advance over to his lawyers to settle his legal bills."
"We have decided to honor that contract and to publish. Once the advance has been earned out, we will continue to honor the contract and pay Julian royalties."
Assange -- whose Web site has been strongly criticized by the United States for publishing sensitive diplomatic communications and documents on the wars in Afghanistan and Iraq -- said the unauthorized publication wasn't a matter of free speech, but simple greed.
"The events surrounding its unauthorized publication by Canongate are not about freedom of information," Assange said in a statement. "They are about old-fashioned opportunism and duplicity -- screwing people over to make a buck."
The draft recounts Assange's early life in Australia, his passion for computers and hacking and the founding of WikiLeaks. Assange worked with a ghost-writer, the BBC said.
On an unrelated matter, Assange is fighting extradition to Sweden on sexual assault allegations. In excerpts of the draft, as he has in other forums, Assange denied the allegations.
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