Blocking the publication of a document on the risks of NHS reforms is a sign that ministers want to downgrade Freedom of Information laws, a watchdog has warned.
The Information Commissioner, Christopher Graham, criticised the Government's decision to exercise its veto, in a report on the case to Parliament.
Andrew Lansley, the Health Secretary, vetoed an Information Tribunal ruling that he should meet Labour demands to publish the Transition Risk Register, which sets out internal government assessments of the dangers posed by the reforms in the Health and Social Care Act.
Mr Graham dismissed Mr Lansley's argument that there were exceptional circumstances and that it involved a matter of principle, saying that the decision "marks a significant step in the Government's approach to freedom of information".
The Department of Health stood by its assertion, saying the Freedom of Information Act "was drafted specifically to allow for the ministerial veto".