Julian Assange, the founder of WikiLeaks, claimed today he was in possession of "insurance" files on Rupert Murdoch and his global media company, News Corporation.

Assange also claimed that WikiLeaks holds more than 500 confidential US diplomatic cables on one broadcasting organisation.

Speaking to journalist John Pilger for an interview to be published tomorrow in the latest edition of the New Statesman, Assange said: "There are 504 US embassy cables on one broadcasting organisation and there are cables on Murdoch and News Corp."

Assange refers to these specific cables as "insurance files" that will be released "if something happens to me or to WikiLeaks".

The Guardian has published stories based on more than 700 of the cables and has access to all 250,000.

He said yesterday that the whistleblowers' site would "shortly" continue publishing cables stories which would "speak more of the same truth to power".

WikiLeaks began publishing the leaked cables through international media partners including the Guardian, part of the group that publishes MediaGuardian.co.uk, in late November.

Their release slowed over Christmas as the partner media organisations, which supplied redacted versions of the documents to WikiLeaks, scaled back their cable operations.

The 39-year-old Australian is currently fighting extradition from the UK to Sweden on accusations of rape and sexual assault. Pilger, who counts Assange as a personal friend, last month offered to stand £20,000 in surety to secure the whistleblower's bail.

Attempts by the US to take legal action against Assange should worry the mainstream media, he said.

"I think what's emerging in the mainstream media is the awareness that if I can be indicted, other journalists can, too," he added.

"Even the New York Times is worried. This used not to be the case. If a whistleblower was prosecuted, publishers and reporters were protected by the first amendment, which journalists took for granted. That's being lost."

Despite pressure from the US on private companies to severe ties with WikiLeaks, Assange insisted that China is the real "technological enemy" of the site.

China has deployed "aggressive and sophisticated" interception technology to stop details of the diplomatic dispatches reaching its citizens, he said, adding that there were now "all sorts of ways" Chinese users could access the controversial material.

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