Singer George Michael claims he was asked to speak to the Leveson Inquiry into press standards but declined, dismissing it as a sham.
As part of a series of tweets posted on Twitter, the star said: "I was asked to talk to the Leveson inquiry, but I declined. It's all bulls**t.
"It has been several years since two hacking journalists were sent to prison for bugging the royal family. They remain the only people who have been tried in the criminal courts.
"After all these years, and all the crimes committed by journos, editors, the police force and MPs the best can do is 'enquiry' after inquiry, and no actual criminal prosecutions?
"Why on earth are the rights of the royal family more important than those of Milly Dowler's parents, or of any of the hundreds of people whose lives have been violated by the press?
"Shame on our political system for it's refusal to take this further. The day they make this sham real and start genuinely prosecuting people I would more than happy to help. :)....till then, what's the point."
During the 15-tweet rant Michael also attacked the Daily Mail, as well as calling Prime Minister David Cameron the "most cowardly PM we've seen for decades".
But a spokesman for the Leveson Inquiry today said George Michael had never been asked to give evidence.
The star's comments come just days before former News International executive Rebekah Brooks and Andy Coulson are expected to make embarrassing revelations about British politicians' attempts to woo Rupert Murdoch's newspapers.
Mr Coulson, David Cameron's former communications director, will appear before the inquiry on Thursday followed by Mrs Brooks on Friday, and their potentially explosive evidence could overshadow David Cameron's efforts to relaunch the coalition's program after bruising local election results for the Conservatives and Lib Dems.
Mrs Brooks is likely to disclose further details about her close relationship with the Prime Minister, while Mr Coulson will speak about how he came to be appointed the Tories' top spin doctor.
Eight Cabinet Ministers - including Mr Cameron, Deputy Prime Minister Nick Clegg and Culture Secretary Jeremy Hunt - were last week given the right to see Leveson Inquiry documents and witness statements in advance.
I was asked to talk to the Leveson inquiry, but I declined. It's all bullst. (sic)
Lord Justice Leveson agreed to make them "core participants", people who have a significant interest in the hearings or may face criticism.
Mr Coulson's appearance will revive awkward questions about the Prime Minister's decision to make the former News of the World editor his communications director.
Mr Cameron said last July that "with 20:20 hindsight" he would not have hired Mr Coulson in May 2007, four months after he resigned from the Sunday tabloid over the jailing of royal reporter Clive Goodman for phone hacking.
Mr Coulson, 44, became Downing Street's communications chief in May 2010 but quit eight months later, saying controversy over the hacking scandal was making his job impossible.
His Leveson Inquiry evidence will be the first time he has spoken publicly since being arrested by Scotland Yard on suspicion of phone hacking and corruption last July. He was bailed and has not been charged.
Mrs Brooks, 43, edited the News of the World and The Sun before becoming chief executive of Mr Murdoch's UK newspapers division News International in September 2009.
She and racehorse trainer husband Charlie are key members of the influential Chipping Norton set, which also includes Mr Cameron and his wife Samantha, Top Gear presenter Jeremy Clarkson, and Mr Murdoch's daughter Elisabeth and her PR guru husband Matthew Freud.
The inquiry has already heard that Mrs Brooks regularly met Mr Cameron and other top politicians along with Rupert and James Murdoch.
She hosted a Christmas dinner on December 23 2010, just two days after Business Secretary Vince Cable was stripped of his responsibility for media takeovers for saying he had "declared war" on the Murdochs' News Corporation empire, and her wedding on June 13 2009 was attended by Mr Cameron and then Prime Minister Gordon Brown.
Mr Cameron said in March that he rode a retired police horse loaned to Mrs Brooks by Scotland Yard from 2008 to 2010.
There is speculation that the Leveson Inquiry could release emails and text messages sent between Mr Cameron and the former News International chief executive.
Mrs Brooks has kept all the texts she received from the Prime Minister, of which there could have been more than 12 a day, according to Daily Telegraph columnist Peter Oborne.
Emails sent by News Corp lobbyist Frederic Michel released by the inquiry have led to calls for Mr Hunt's resignation over claims he secretly backed the Murdochs' BSkyB takeover bid.
Mrs Brooks has twice been arrested by Scotland Yard detectives investigating allegations of phone hacking, corrupt payments to public officials, and an attempt to pervert the course of justice. She was bailed and has not been charged.