Lord Justice Leveson today made an order banning advance publication of documents submitted to his press standards inquiry after Alastair Campbell's witness statement was leaked to a blogger.
Paul Staines, who blogs under the name Guido Fawkes, posted a draft of the former Number 10 communications director's written evidence online yesterday.
Lord Justice Leveson said he was "concerned" about the security of the inquiry's computer systems, which hold witness statements and other confidential documents which are only accessible to those involved in the hearings.
He said he intended to require Mr Staines to give evidence this week about how he obtained Mr Campbell's statement.
Pointedly not referring to the Guido Fawkes blog by name, the inquiry chairman said: "I am concerned to deprive the particular website of that oxygen."
Lord Justice Leveson asked the lawyers representing the inquiry's "core participants" - people who have a significant interest in the hearings or may face criticism - to review their arrangements to ensure that witness statements are kept confidential.
"I am obviously concerned about the security of the information that is available and to maintain the integrity of the inquiry as we move forward," he said.
"As a result I am intending to inquire to such extent as I can into the circumstances in which this statement came to be available for publication."
Lord Justice Leveson also made an order under section 19(2)(b) of the Inquiries Act intended to stop future publication of documents leaked from his inquiry.
The order reads in draft form: "No witness statement provided to the inquiry, whether voluntarily or under compulsion, nor any exhibit to such statement, nor any other document provided to the inquiry shall be published or disclosed, whether in whole or in part, outside the confidentiality circle comprising of the chairman, his assessors, the inquiry team and the core participants and their legal representatives, prior to the maker of the statement giving oral evidence to the inquiry or the statement being read into evidence or summarised into evidence by a member of the inquiry team as the case may be, without the express permission of the chairman."
Mr Staines, whose Order-Order blog combines political gossip and comment with some genuine news scoops, claims to have obtained Mr Campbell's witness statement "by legal means".