British Justice Secretary Jack Straw has vetoed the publication of minutes of key Cabinet meetings held in the run-up to the Iraq war in 2003.
Mr Straw said he would use a clause in the Freedom of Information Act to block the release of details of meetings in which the war's legality was discussed.
He said releasing the papers would do "serious damage" to the executive and outweighed public-interest needs.
The Information Tribunal ruled last month that they should be published.
The tribunal rejected a government appeal against a ruling by the Information Commissioner that the papers be published because decisions taken in the run-up to 2003 invasion of Iraq were "momentous" and controversial.
Mr Straw told MPs he had not taken the decision to block the minutes lightly. The decision was approved by Cabinet.
But he said it was necessary in the interest of protecting the confidentiality of ministerial discussions which underpinned Cabinet decision-making and collective responsibility.
The Conservatives said the decision was right because release of the minutes would make ministers more reluctant to discuss controversial subjects in future, impeding good government.
The BBC reports that Cabinet minutes are not normally released until at least 30 years after the event.