Sir Richard said the Government's defence of the use of Public Interest Immunity certificates - the so-called "gagging orders" - in criminal cases such as the Matrix Churchill trial was "unacceptable".
He said he felt a sense of "depression" that ministers were continuing to argue that whole classes of Government documents should be withheld simply because disclosure might affect the "candour" of the advice given by their officials.
And he dismissed the Government's claim that the inner workings of the Whitehall machine should not be exposed to ill-informed public criticism.
"The secrecy with which Government chooses to surround its inner workings, with light cast only by designer leaks and investigative journalists, is not, in my opinion, a reason for perpetuating the sort of PII class claims that were made in the Matrix Churchill cases."
Sir Richard's attack came in the latest of a series of lectures he is giving on his inquiry - his first public comments about PIIs since the publication of his report last month.
In their response to his recommendations on PII, ministers said "the inner workings of the Government machine" should not be exposed to the gaze of those without adequate knowledge of the background and perhaps with some axe to grind.
However, Sir Richard, addressing the Public Law Project in London, insisted that the acceptance of ill-informed criticism was the price that had to be paid for a democratic and open system of Government.
"If Government insists on secrecy for the `inner workings of the Government machine', is it in a position to be surprised if criticism is ill-informed?"
He also rejected the Government's argument that officials would not feel free to give candid advice to ministers if they thought that their advice might become public. "I feel a sense of some depression that this candour argument is still being strongly relied upon," he said.
Sir Richard warned that the continued sanctioning of PII class claims would only serve to increase Whitehall secrecy as ministers and officials sought to withhold more and more classes of documents.Reuse content