The Independent editor Chris Blackhurst fears Lord Justice Leveson is 'loading a gun'and preparing to launch a 'damning indictment'of the national press when his report comes out in the autumn.
Leveson sent a letter to all national newspapers this week warning them of potential criticisms that could feature in the report.
Blackhurst said his reaction to the letter, which runs to more than 100 pages, was one of 'shock and anger", describing the document as a 'diatribe".
'I suppose if I was to summarise, and I think I can, it throws the book at the industry,'he told BBC 4's the Media Show.
'No titles are singled out and no individuals are singled out, but it basically is a point-by-point demolition of the industry."
While the document was not written in 'red-blooded terms", said Blackhurst, as an overall picture it was a 'damning indictment of my industry".
'From the point of view of my own paper, The Independent, there's an awful lot in there that we just don't recognise in relation to ourselves,'he said.
'I can't speak for other groups but I think some of the titles at our end of the market surely must feel the same way. There's things in there we simply have not done."
Blackhurst said the letter was almost entirely negative, before launching this defence of the industry: 'The fact is that newspapers are an adornment to our society – we would be lost without them.
'They do fantastically good work and I don't just mean my own newspaper, I mean… the tabloids as well
'Story after story, scandal after scandal has been broken by newspapers, not by anybody else, and that simply isn't reflected in that document."
Blackhurst said the letter made him genuinely worried about the outcome out the inquiry, but admitted it was not clear 'whether this is the worst it can get, and now he's going to start reining back".
'The best way I can describe it is he's loading a gun and this document of well over 100 pages is all the ammunition, and believe you me there's plenty of ammunition,'he said. 'You read it and you just gulp."
Last night an inquiry spokesman issued the following statement: 'Lord Justice Leveson is disappointed that the contents of confidential letters that he has written are being openly discussed in the Press.
'He wants to make it clear that all recipients of these letters – which are issued in accordance with Rule 13 of the Inquiry Rules 2006 – are obliged by this confidence."
Under Rule 13 of the Inquiry Rules 2006, Leveson must give a right to reply to those he intends to criticise in his final report.
According to reports, the letters are inherently one-sided because they are solely concerned with giving individuals or companies the chance to explain why such criticism should not be contained within the final report.