The Blair Government has obtained court injunctions against newspapers before but it has never prosecuted editors for publishing the contents of leaked documents.

Under a front-page headline “Bush plot to bomb his ally” in the Daily Mirror yesterday, a secret minute of the conversation in April 2004 records the President allegedly suggesting that he would like to bomb the channel’s studios in Doha, capital of Qatar. Richard Wallace, the Editor of the Daily Mirror, said last night: “We made No 10 fully aware of the intention to publish and were given ‘no comment’ officially or unofficially. Suddenly 24 hours later we are threatened under Section 5.”

According to the Mirror, the transcript turned up in the office of former Labour MP Tony Clarke, who lost his Northampton South seat in May.

His former researcher and a Cabinet Office official, accused of breaking the Official Secrets Act, will appear at Bow Street Magistrates’ Court.

Downing Street refused to comment on the matter yesterday, saying that it was sub judice.

Last night Peter Kilfoyle, the Labour MP for Liverpool Walton and a former Defence Minister, tabled an early day motion urging Mr Blair to publish the conversation. He said that what Mr Bush said was a “matter of great interest” to MPs and the public.

Al-Jazeera has angered the US Administration by broadcasting video messages from Osama bin Laden and footage of dead and injured Iraqi civilians.

The White House called the reports “outlandish”. “We are not going to dignify something so outlandish with a response,” an administration official said.

But Mr Kilfoyle said that if there was a record of a conversation where an attack on al-Jazeera’s headquarters was mentioned, MPs should know about it.

He also dismissed comments by Whitehall officials that any suggestion of an attack would have been in jest.

“This is a matter of great interest. There was an attack on the hotel in Baghdad used by al-Jazeera journalists which caused great controversy. The US also attacked a Serbian TV station (during the Kosovo war). It is easy to dismiss this as a glib comment, but I don’t find it very funny at all,” he said.

Mr Clarke, who was against the war in Iraq and lost his seat at the last election, returned the document to the Government. “As well as an MP, I am a special constable,” he said.

Charges under the Official Secrets Act have to be approved by the Attorney-General. His involvement suggests the prosecution intends to hold part, if not all, of the trial, behind closed doors.

On Newsnight last night, a spokesman for al-Jazeera defended the channel’s output.

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