- WikiLeaks founder Julian Assange threatened to sue Britain's Guardian newspaper for allegedly giving his website's cache of classified U.S. cables to the New York Times, according to two new books.

The accounts by journalists for the Guardian and German magazine Der Spiegel describe their publications' turbulent relations with the mercurial WikiLeaks founder.

Assange, an Australian-born computer hacker, became an international celebrity last year after his website acquired, and began to make public, hundreds of thousands of secret U.S. government documents.

The Guardian and Spiegel journalists' books are part of the first wave of what could become a flood of writings, documentaries and feature films about the WikiLeaks phenomenon and Assange, its colorful figurehead.

Other publications either in the works or already released include an e-book put together by the New York Times, The Age of WikiLeaks, by Greg Mitchell, a blogger for The Nation magazine, and Assange's own book, for which he reportedly received an advance of around $1.5 million.

Earlier this week, Norwegian parliamentarian Snorre Valen nominated WikiLeaks for the 2011 Nobel Peace Prize, saying the website had become one of the most important contributors to freedom of speech and transparency in the 21st century.

LEGAL THREAT

Both the Spiegel and Guardian journalists' books describe a November 1, 2010 meeting at which Assange threatened the Guardian with a lawsuit over what he alleged was a breach of a deal he thought he had with the newspaper.

Assange showed up with two lawyers. The WikiLeaks creator felt that a breach of contract had taken place, which is why he had brought along his attorneys, Spiegel journalists Marcel Rosenbach and Holger Stark report in their book, entitled Staatsfeind WikiLeaks (WikiLeaks, Public Enemy No. 1).

According to the Spiegel account, Assange last summer signed a written agreement with the Guardian in which the newspaper agreed that WikiLeaks was providing the diplomatic cables to it for review and that the paper could not duplicate or publish them without WikiLeaks' permission.

According to both Spiegel's account and the account of Guardian journalists David Leigh and Luke Harding in WikiLeaks -- Inside Julian Assange's War on Secrecy, Assange sought to cut out the New York Times from WikiLeaks' cache of diplomatic cables after the newspaper ran an unflattering profile of him.

The Times had earlier collaborated with the Guardian and Der Spiegel on the publication of classified U.S. military reports related to the wars in Afghanistan and Iraq.

Guardian and Spiegel executives wanted to continue their collaborative relationship with the American newspaper.

By late October, the Guardian had acquired copies of the cables from a second source not directly beholden to Assange. This led the British paper's editorial executives to conclude they were no longer bound by any deal about the material which they had previously agreed with Assange.

WIKILEAKS LEAKED

Without Assange's consent, the Guardian went ahead and provided the Times with the State Department material.

According to the book by the Spiegel journalists, who attended the November 1 meeting, Assange used words like theft and criminal activities when talking about distribution by the Guardian and others of the WikiLeaks State Department hoard.

The Guardian journalists' book says that Assange, an underground leaker of illegal secrets, threatened that his lawyers could sue for the loss of Wikileaks' financial assets. WikiLeaks has been leaked, that's the truth, declared Guardian editor Alan Rusbridger, according to the Spiegel journalists' account.

According to the Guardian journalists' account of the meeting, Rusbridger's response to Assange's legal threat was: I'd look forward to such a court case.

A lawyer for Assange who attended the November 1 meeting, Mark Stephens, did not immedately respond to requests for comment.

The New York Times has published its own book-length account of its dealings with WikiLeaks and Assange and its handling of documents he provided to the paper.

Last month, the Times published Keller's own lengthy account of his and the paper's dealings with Assange.

He offered several reasons why the paper's relationship with the WikiLeaks founder soured, including a decision by the Times to refuse to link its website directly with WikiLeaks.

(Editing by Andrew Roche)