WikiLeaks founder Julian Assange has launched an attack on the Press Complaints Commission, claiming he has been subjected to inaccurate and negative media coverage "possibly on a scale not seen since the abuse of the McCanns".

He says the soon-to-be-extinct complaints body stood idly by as he "suffered extensive libels" in the coverage of his battle with Swedish authorities over sexual assault allegations.

Assange, who is out on bail awaiting a British court decision on his appeal against extradition to Sweden, has told the Leveson inquiry says the PCC found it "perfectly acceptable for newspapers to say that I had been charged with rape as being 'charged' with an offence is seen as the same as a mere allegation".

In a written statement to the inquiry he said his experience with the PCC provides a "unique" case study at the damage that can be wrought by a flawed regulatory system to an individual involved in a "high profile and political" situation.

Assange added: "Press standards matter. Those who have been the subject of ongoing, widespread inaccurate and negative media coverage – as I have, possibly on a scale not seen since the abuse of the McCanns – know that the harms created for individuals and small organisations or groups by a failure to maintain high ethical journalistic standards can be severe, consequential and almost insurmountable."

He told how he complaint about 45 articles in newspapers including the Observer, the Guardian, the Daily Mail, the Independent, the Evening Standard and the Sun, which he referred to "charges" against him or said he was "facing charges" or had been "charged".

The PCC's found that no breach of its code of practice had occurred.

Assange wrote: "The PCC's clear failure to enforce proper standards of accuracy and fairness – indeed, its reluctance to act and to adhere to its own guidelines because of the active case against me – comes at a time when, due to the number of other of our legal cases already in play and my grave personal circumstances under house arrest awaiting a supreme court extradition decision, my ability to achieve justice through libel actions at the moment when they are needed is severely curtailed."

He said the "libels and inaccuracies" affect "the political climate and community support in which a politicised extradition treaty is occurring".

His statement added they have also affected WikiLeaks case against the banking blockade being considered by the European commission and on the support for the site, including the willingness of lawyers to do pro bono work.

He said people libelled by newspapers in the UK face a stark choice for justice: "prohibitively expensive litigation" or redress to the complaints body.

"The PCC fails to provide individuals vulnerable to bad journalistic practice … with effective protection or redress," he added.

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