Journalist John Pring is not a household name, but for those affected by benefit cuts, particularly those with disabilities, he is something of a hero.

The news agency he operates, Disability News Service, is a very modern phenomenon - funded partly by advertising and individual subscribers, but mostly by disability charities, which use the stories he writes to help spread up-to-date information and support campaigns on welfare reform.

Newspapers have used his work in print and online. Scottish disability rights group Black Triangle used his research as part of its successful campaign to inform doctors about the damage cuts are doing to some of their patients, and explain to them what they can do about it.

DNS has also embarrassed disability minister Mark Harper, running stories about the lack of wheelchair access at some disability assessment centres, and his own constituency office at the same time as Harper was handing out awards for accessibility.

Pring has relentlessly highlighted problems with Work and Pensions minister Iain Duncan Smith's flagship Universal Credit programme and revealed that the Department for Work and pensions (DWP) had secretly investigated more than 60 deaths of benefit claimants since 2012, without publishing the findings or more than 30 resulting recommendations for change.

Mr Pring's work is in many ways classic investigative journalism, and the DWP does not dispute that he always sought a comment from them in response to his findings.

However last week the DWP's press office ceased to deal with DNS and says it will no longer respond to it as a bona fide news organisation. When Mr Pring asked for a comment on the news that the Information Commissioner in England was to investigate the DWP's refusal to publish details of internal reviews of benefit-related deaths, a civil servant told him no comment would be forthcoming.

This appears to have been triggered by stories published by DNS which left out comments from the Government. Mr Pring says this is because press officers missed deadlines, the DWP says he should publish corrections. Because the queries DNS submits are complex, they take time to answer, and if that time is wasted, that takes away from time needed to answer queries from other newspapers, broadcasting and other news agencies.

The problem is those other journalists very often depend on such grassroots reporting. Benefit reform is complex and affects people who are vulnerable and marginalised. Many are afraid to speak up about their treatment by job centres and work programme providers for fear (rightly or wrongly) that it may make matters worse for them.

Many reporters lack the detailed understanding of the system held by John Pring - who is himself disabled - and the work he does helps keep a vital issue in the public eye.

Mr Pring says the decision undermines his credibility, could affect his livelihood and is essentially discriminatory.

Supporters, of which he has many, argue that by refusing to communicate with John Pring the DWP is refusing to communicate with millions of disabled people.

The DWP says it is only asking him to adhere to the same standards as other journalists it deals with. But those who rely on him for information believe it looks suspiciously as if the department is petulantly withdrawing cooperation from an arch critic.