Guido Fawkes has been summoned to appear in front of the Leveson inquiry.
The news came after the political blogger, also known as Paul Staines, published a leak of former Number 10 spin chief Alastair's Campbell's evidence to the inquiry on his order-order.com website.
The inquiry into press standards released a statement on Sunday saying it was "extremely concerned" about the leak.
"Lord Justice Leveson was extremely concerned to hear that, on November 27 2011, a copy of the evidence that Mr Alastair Campbell intended to provide to the inquiry was published on the 'Guido Fawkes' website.
"The website asserts that this statement was obtained by 'legal means' but Lord Justice Leveson will be enquiring further into this claim and Mr Paul Staines will be required to give evidence."
Campbell said on Sunday he was "genuinely shocked" his statement had been leaked and accused Fawkes of misrepresenting his evidence with his headline.
Earlier the blog had posted its intention to "demonstrate the freedom of the press, in the internet age, empirically. Contra Leveson…."
Staines will join celebrities Hugh Grant, Sienna Miller and author JK Rowling who all given evidence to the inquiry.