Max Mosley, the former Formula One Boss turned privacy campaigner following a News of the Word sting, has told MPs he supports "cutting the wires" to internet sites who publish "the worst" pieces in breach of press regulation.
He was speaking alongside press regulation campaign group Hacked Off at Department of Culture, Media And Sport select committee into press regulation, 24 hours after MPs agreed a landmark Royal Charter.
Responding to a discussion about the impracticality of regulating sites based abroad, Mosley suggested that the British public could be banned from seeing such sites, if they routinely break British codes of conduct or publish falsehoods.
"Of course in the worst case you can, figuratively speaking, cut the wire. An order of the English court is enforceable in England. Of course nobody wants to do that," he said.
He added: "But don't pretend it's not practical, because it is."
Index on Censorship's chief executive Kirsty Hughes said: "Closing down websites is the kind of behaviour expected of totalitarian regimes likes Iran and China, not the UK.
"From the start of the Leveson Inquiry, Index has voiced concerns about the failure to take the internet into account in discussions about press regulation, and we are worried that the Royal Charter will be used to chill the speech of bloggers and journalists online."
In 2008 Mosley won a court case against the now defunct News Of The World, which published pictures of him with prostitutes, on the grounds that it had breached his privacy.
Mosley later tried to stop Google searches from returning web pages which referenced the News of the World story, even though Google do not host the web pages.
Hugh Tomlinson, the chair of Hacked Off, said people were always going to be able to avoid regulation, but that was not a problem. The goal is about "capturing" the majority, he said.
"People have always managed to avoid restrictions, I don't think we need to think about them, we need to think about the vast mainstream of people who do want to do the right thing who do want to obey the rules," he said.
Seamus Dooley, Assistant General Secretary of the National Union of Journalists said the trade union approved the new Charter.
"If you look at the Bill, it is not state regulation. What we have is a guarantee of quality and ethical journalism, and it is a pity the media did not embrace Leveson earlier on," he said.
"I would defend the hacking of a phone that served the greater public interest, I would have no problem with journalist stretching it to the limits. But what Leveson showed was that it was done to increase profits.
"It is simplistic to believe that the greatest challenge facing journalism is this Royal Charter."