The government has vetoed an order by the independent freedom of information watchdog to release the minutes of cabinet meetings held immediately before the invasion of Iraq in March 2003.
The decision was announced on Tuesday by Dominic Grieve, the attorney general, the only minister to have access to papers of a previous administration, in this case Tony Blair's Labour government.
Grieve said he issued a certificate under the Freedom of Information Act vetoing disclosure after consulting former Labour ministers, his cabinet colleagues, and the leader of the opposition, Ed Miliband.
He described the case as "exceptional" and one where, in his view, the public interest demanded the papers should be kept secret. He says he took into account "serious potential prejudice to the maintenance of effective cabinet government".
The attorney said he also considered the fact that "the issue discussed was exceptionally serious, being a decision to commit British service personnel to an armed conflict situation", that the issue "remains the focus of both domestic and international interest", and that "Iraq remains very much a live political issue in its own right" with links to the "overall security situation in the Middle East and the perceived link between the terror threat to the UK and military action in Iraq".
Grieve noted that most of those present at the cabinet meetings in March 2003 were still MPs or "otherwise active in public life".
Christopher Graham, the information commissioner, had argued that the "exceptional gravity and controversy" of the matters discussed meant that minutes of the cabinet meetings on 13 and 17 March 2003, days before the invasion, should be disclosed.
One of the reasons Grieve gave for vetoing disclosure was that the Chilcot inquiry meant the invasion of Iraq was still a "live" issue. Yet the panel chaired by Sir John Chilcot is being prevented by Whitehall mandarins from disclosing key documents relating to the decision to invade Iraq.
The March 2003 cabinet minutes are believed to be among them. The continuing dispute between Chilcot and Whitehall officials over disclosure is a main reason why his report has been delayed.
In a separate move last week, the Foreign Office appealed against a judge's ruling that extracts of a conversation between Blair and George Bush days before the invasion of Iraq must be disclosed. It argued that revealing Blair's comments to Bush on the telephone on 12 March 2003 would present a "significant danger" to UK-US relations.
A spokesperson for the information commissioner said on Tuesday that Graham was disappointed that a ministerial veto had been used "to override his recent decision notice concerning the minutes of two cabinet meetings held immediately prior to the commencement of military action in Iraq in 2003".
Grieve was asked through Freedom of Information Act requests to overturn a decision in 2009 by Jack Straw, then justice minister, to suppress the cabinet minutes. Straw vetoed disclosure on the grounds that in cabinet meetings "dialogue must be fearless" and "cabinet decision-making could increasingly be driven into more informal channels with attendant dangers of lack of rigour, lack of proper accountability, and lack of proper recording of decisions".
However, the Chilcot inquiry has heard evidence from former Labour cabinet ministers, senior Whitehall officials and law officers, that the Blair government took decisions – including those relating to the invasion of Iraq – without informing the cabinet and without taking a proper record of decisions.
The earlier Butler inquiry into the use of intelligence on Iraq strongly criticised the Blair government's decision-making procedures in its report published in July 2004