THE US is wrong to charge Julian Assange for publishing unredacted classified documents because they had already appeared online beforehand, the extradition hearing for the Wikileaks founder heard today.

Computer scientist Professor Christian Grothoff said that Wikileaks was not the first to release 251,000 diplomatic cables when they appeared on its website on September 2 2011.

Mr Assange, 49, is fighting extradition to the US, where he faces an 18-count indictment alleging a plot to hack computers and conspiracy to obtain and disclose national defence information.

Prosecutors claim that he put the lives of sources and informants around the world at risk by publishing their names.

But Prof Grothoff told the Old Bailey that the unredacted cables came into the public domain after the publication of a passcode in a book by Guardian journalists in February 2011.

He said that in late August 2011, it was discovered that the code could be used to decrypt a version of the cables held by Wikileaks before the full cache was made available through the Pirate Bay and Cryptome websites on September 1.

“It was actually available on the internet in a way that would be virtually impossible to stop,” Prof Grothoff told the court via video link.

But the expert’s impartiality was called into question by the US government because his name appears on a 2017 letter to Donald Trump urging the president not to charge Mr Assange or other Wikileaks staff.

Prof Grothoff said that he did not remember signing the letter but described Mr Assange as a “sympathetic character” because of his role in exposing “war crimes.”

Joel Smith, prosecutor for the US government, probed: “You are biased, you are partial?”

Prof Grothoff replied: “No. I believe that looking at the indictment put forward, you’re confusing actions Wikileaks took to hide and obscure the documents with them publishing it.

“On the very specific technical point where you say Wikileaks published those cables you are wrong, and you didn’t properly do your homework to find who first published those cables.

“So I think it’s unfair for you to accuse Mr Assange of publishing those unredacted classified cables.

“The primary publisher of the unredacted cables wouldn’t be Wikileaks.”

The hearing, which entered its third week today, continues.