David Cameron's plans for new laws to regulate the press "run counter to bedrock principles of a democracy", some of American's most eminent journalists have warned.
In a letter to the Prime Minister, the Campaign to Protect Journalists (CPJ) urges Mr Cameron to "step back" from creating a new regulator as it would set a bad example to repressive dictatorships.
The idea of a regulator underpinned by statute was proposed by the Lord Justice Leveson's inquiry into media ethics in the wake of the phone-hacking scandal. Mr Cameron has signalled he belives the plans strike an acceptable balance between protecting victims of media intrusion and preserving freedom of expression.
But the letter, signed by the campaign's executive director Joel Simon, warns that Britain could lose its "moral authority" on press freedom if it goes ahead with the plans.