The government has been told it must publish one of the risk registers drawn up for the latest round of NHS reorganisation and reform.

An Information Tribunal has rejected an appeal from the Department of Health against an order from the Information Commissioner’s Office to publish transition risk register, which focuses on the threats posed by the reforms.

It said the government could keep secret a second register; the strategic risk register, which covers ongoing threats to the service.

Labour has now called on Prime Minister David Cameron to order the immediate release of the register; although the government could delay it until after the next round of Parliamentary debate on the bill, or even mount a further appeal.

Top officials from the Cabinet Office and the DH told the tribunal that releasing the register would have an “insidious” effect on the work of officials and the advice given to ministers.

They also argued that the register might be misunderstood, and that changes had anyway been made to the Health and Social Care Bill since it was drawn up.

The ICO ruled last November that the arguments against publishing the register were outweighed by those in favour of publishing it.

Tom Healey, the Labour minister who mounted the initial campaign for the register to be released, said the government should now release it and “let people make up their own minds on the NHS changes.”

However, the DH said it was waiting for the detailed reasoning behind the tribunal’s decision, and would then “work with colleagues across government to decide next steps.”

Liberal Democrat activists are pushing for a debate on the bill at their spring conference this weekend, and critical votes on the much-amended legislation are due to be held in the House of Commons on Tuesday.

Risk registers released by the four cluster strategic health authorities suggest they are worried the reforms will destabilise organisations, increase costs, decrease patient safety, and put specific initiatives at risk. The cluster SHA for the North of England identified IT as one of these risks.