The public will have no right to see details of private disputes between ministers or embarrassing rows in Cabinet, despite the introduction of new disclosure laws.
The Freedom of Information Act came into force yesterday, backed by promises that it would dispel the secrecy in Whitehall and introduce a new spirit of government openness. But the Government has ordered that personal emails and letters - even those relating to serious policy arguments - will be kept private.
Under the Act, the public can request confidential files held by 100,000 public bodies, including government departments, schools and police forces. This includes unpublished documents relating to such sensitive issues as the BSE crisis and the war in Iraq.
However, Lord Falconer, the Lord Chancellor, who is overseeing the introduction of the new law, said: "Ministers should be able to correspond with each other and disagree with each other but that should not become public because you could always identify which minister disagreed with which policy - people accept you need that sort of space in which to govern."
There are exemptions under the Act, including information held by the security services. Ministers also have the power to veto disclosures. No decision has yet been taken on releasing the Attorney General's advice to the Government on Iraq. Lord Falconer said the case will be looked at on its merits if officials receive a request.
Officials have had four years in which to prepare themselves for the new law, but are bracing themselves for a flood of requests. Authorities should reply to requests within 20 days but campaigners are concerned about potential delays.
Lord Falconer said he could "guarantee" every request would be met on time although he admitted some schools and hospitals were not ready. He accepted that "there are particular bodies" that were not well prepared, but said: "Everybody's had four years to prepare - there really is no hiding place."
Some Government departments have already published documents online which they think are of public interest. These include MRSA rates for individual hospitals and the location of speed camera sites with casualty rates for each.
Lord Falconer said the power of veto would be used "very exceptionally" with full cabinet approval and that detailed reasons for the veto would be given to Parliament.
The Conservatives' defence spokesman, Julian Lewis, accused the Government of systematically destroying thousands of potentially sensitive documents ahead of the Act's implementation.