LONDON—WikiLeaks founder Julian Assange has agreed to write a memoir, U.S. publisher Random House confirmed, receiving an advance that Mr. Assange said totals more than $1 million for U.S. and U.K. rights as he seeks to pay mounting legal bills and keep the document-leaking website in the black.

Random House, a unit of Germany's Bertelsmann AG, expects the manuscript to be delivered at some point in 2011 but doesn't yet have a timetable for publication, Paul Bogaards, a spokesman for the U.S. publisher, said Sunday.
""We are very excited to be publishing this book,"" said Mr. Bogaards, a spokesman. ""The work that Assange has been doing at WikiLeaks has tremendous importance around the world.""
In an interview published Sunday with U.K. newspaper the Times, Mr. Assange said he would receive £325,000 ($502,000) from U.K. publisher Canongate Books Ltd. and $800,000 from U.S. publishing house Alfred A. Knopf, itself a unit of Random House, for writing an autobiography.
Mr. Assange said he expected to make at least £1.1 million after the book was serialized and sold to other international publishers.
Neither publishing house confirmed the amount of the deal.
Mr. Assange, who has become a controversial figure after leaking thousands of confidential U.S. State Department cables on his website, is in the midst of a legal battle with Swedish authorities, who want him extradited to Sweden from the U.K. for questioning in connection with allegations of sexual misconduct.
The 39-year-old Australian, who is under house arrest in rural England as he awaits an extradition hearing early next year, has denied the accusations and dismissed them as a smear.
""I don't want to write this book, but I have to,"" Mr. Assange told the Sunday Times. ""I have already spent £200,000 for legal costs and I need to defend myself and to keep WikiLeaks afloat.""
Mr. Assange couldn't be reached to comment Sunday.
Word of Mr. Assange's book deal first came in the middle of last week on the Twitter feed of Claudio López de Lamadrid, literary publisher at Random House's Spanish-language joint venture Random House Mondadori SA. ""J. Assange has sold his memoirs,"" Mr. López wrote on Twitter on Dec. 20. ""Canongate and Knopf will publish in the UK and USA. Manuscript completed in March.""
A spokeswoman for Canongate declined to comment. Canongate, a small independent publisher based in Edinburgh, in 2006 picked up the rights to Barack Obama's books, ""Audacity of Hope"" and ""Dreams From My Father,"" some six months before the then-U.S. senator announced his presidential bid. The publisher paid a five-figure sterling sum for each title.
Photo: Wikileaks founder Julian Assang