Singer George Michael was called to testify at a hearing into media standards in Britain but declined, branding the official probe a "sham".
The former Wham! star refused to give evidence at the U.K.'s Leveson Inquiry, which was set up to re-examine press controls in the wake of the News of the World phone hacking scandal.
A string of high-profile stars who claim to have been unfairly targeted - including Hugh Grant and Charlotte Church - have all taken the stand, but tabloid favourite Michael is adamant he wants no part in the probe.
In a post on Twitter.com, he writes, "I was asked to talk to the Leveson inquiry, but I declined. It's all bulls**t."
Michael went on to criticise British authorities for failing to bring charges against those accused of phone hacking, adding, "After all these years, and all the crimes comitted (sic) by journos, editors, the police force and MPs... The best (they) can do is 'enquiry' after inquiry (sic), and no actual criminal prosecutions?...
"Shame on our political system for its 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."