A powerful Westminster committee is to launch an inquiry into a secretive unit at the heart of government that has been accused of ‘blacklisting’ Freedom of Information (FOI) requests sent by journalists, campaigners and researchers.

The public administration and constitutional affairs committee (PACAC) is to announce a probe into the Cabinet Office’s controversial ‘Clearing House’ unit, and the operation of FOI across Whitehall, openDemocracy understands.

The investigation comes after openDemocracy won a legal victory, forcing the Cabinet Office to disclose information about the “Orwellian” unit run by Michael Gove’s department.

Judge Chris Hughes said that there was a “profound lack of transparency about the operation”, which might “extend to ministers”.

The inquiry will examine the Clearing House operation and the wider state of FOI across government.

The exact terms of the probe have yet to be confirmed. It is expected that a short, targeted inquiry will be held either directly before or after the summer recess.

Michael Gove is expected to be called to give evidence.

The Cabinet Office minister has previously dismissed concerns about government secrecy, telling the PACAC in December that “the idea that there is a secret Clearing House or any sort of blacklist is ... not correct.”

Judge Hughes criticised the Cabinet Office, however, for a “launca in public information” about how the Clearing House coordinates FOI requests and said that documents presented by Gove’s department had “misled” the tribunal.

The decision to hold the inquiry comes after a number of press freedom and transparency campaigners, including the National Union of Journalists and the Campaign for Freedom of Information, wrote to the PACAC’s chair William Wragg, calling for an investigation into FOI.

The proposed FOI probe was unanimously supported by all 11 MPs on the committee. openDemocracy’s legal judgement was cited by some PACAC members when they met in private on Tuesday morning.

Michelle Stanistreet, general secretary of the National Union of Journalists, welcomed the parliamentary investigation. “It’s time to get to the bottom of this and find out exactly what has been happening," Stanistreet said.

Katherine Gundersen deputy director of the Campaign for Freedom of Information said: "FOI is in poor health, with requests suffering from prolonged delays and government hostility.  For PACAC to look into FOI is a much needed of sign of renewed Parliamentary interest in this vital legislation.”

openDemocracy had previously revealed that the Clearing House has blocked the release of politically sensitive information, in one instance comparing the handling of an FOI request to the Chilcot Inquiry into the Iraq war.

Last week, Labour’s deputy leader Angela Rayner demanded that the prime minister’s independent standards advisor launch an investigation into whether Gove had broken the ministerial code in his statements to Parliament about the secretive unit.

Lord Clark, an architect of the original FOI act, branded the government’s approach to transparency “a joke” after the international trade department mistakenly revealed details of how Clearing House officials had worked to block information from being released to journalists.

Data protection experts have also warned that the Clearing House lists – which are circulated daily across Whitehall with details of journalists and other people making FOI requests – could be breaking the law.

The Cabinet Office went to court in a bid to block openDemocracy’s three-year-long battle for transparency over the Clearing House unit. Gove has previously called openDemocracy’s journalism “ridiculous and tendentious” but his department has now been ordered to release further details about the secretive unit

The ruling came in an information tribunal case brought by openDemocracy, along with the public interest law firm Leigh Day. During the hearing, the Cabinet Office had offered an out-of-date Wikipedia entry as evidence that information about the FOI unit was available to the public.

In February, a dozen current and former Fleet Street editors as well as more than 100 journalists, researchers and campaigners signed openDemocracy’s open letter calling for “urgent” action over FOI and for an investigation into the Clearing House operation.

A Cabinet Office spokesman has previously said: “All FOI requests are treated exactly the same, regardless of who the request is from and their occupation. It would be unlawful for the Cabinet Office, or any other public authority, to blacklist or vet inquiries from journalists. Departments may refer round-robin or requests for sensitive information to the Cabinet Office for advice on how to respond.”