Lord Goldsmith threatened newspapers on Tuesday with prosecution under the Act if they published details from a record of a conversation between Mr Bush and Tony Blair from April last year, when the President is alleged to have suggested bombing al-Jazeera, the Arabic television network.

A record of the conversation was leaked by a Cabinet Office official to the researcher of an MP, and details appeared in a newspaper this week. Both men have been charged under the Official Secrets Act and will appear in court next week.

Mr Blair’s Government has never threatened newspapers with prosecution under the Act, lawyers say. This is despite numerous leaks of documents relating to the war in Iraq, including the Attorney-General’s own legal advice on the war.

That led to accusations from MPs yesterday that the Act was being used to avoid further embarrassment to Mr Bush over Iraq rather than to protect Britain’s security.

“In my view I can see no other explanation for this than an overwhelming desire to placate President Bush and prevent him being embarrassed,” Peter Kilfoyle, the Labour MP for Liverpool Walton, said. He has tabled a motion calling on the Government to publish the record of the conversation.

The Liberal Democrats said that the Government was wholly inconsistent.

“The immediate question is why the Attorney-General should think it necessary to use the big stick on this occasion,” Sir Menzies Campbell, the Liberal Democrat foreign affairs spokesman, said. “The suspicion is that this is not so much in the national interest but more in preserving the Government from further embarrassment.”

Whitehall sources last night denied that the White House had put the Government under pressure to act. Sources who have seen the documents say that it is clear the discussion on bombing al-Jazeera is not serious.

AN INDEX OF CENSORSHIP

DA NOTICES Voluntary system of guidance on what can be published. But newspapers can be prosecuted even if they have been led to believe a story complies

OFFICIAL SECRETS ACT Allows the Government to prosecute newspapers under criminal law — but is predominantly for gagging rogue officials. David Shayler, above, the former intelligence expert, was recently prosecuted under the Act and served a prison sentence

LAW OF CONFIDENCE The Government’s usual method to stop sensitive intelligence slipping out. A civil action with huge financial considerations for newspapers

CONTEMPT OF COURT The Attorney-General has taken to issuing regular guidance to editors in cases where he feels that there may be a risk of serious prejudice to a trial

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