Statement said attorney general acted in 'public interest capacity'

The injunction was obtained on Friday night at a hearing which lasted about two hours at the Royal Courts of Justice in London.

Lord Goldsmith's office said he had acted "completely independently of government" on the matter.

The BBC said its reporting of the story was a matter of public interest.

BBC media correspondent Torin Douglas said it was understood to be the first injunction to be sought or granted in connection with the cash for honours investigation.

'Specific request'

The attorney general's office and the Metropolitan Police issued a joint statement on the matter.

In it, they said the application for an injunction was made by Lord Goldsmith "at the specific request of and in co-operation with the police because of their concerns that the disclosure of certain information at this stage would impede their inquiries".

That statement added: "The attorney general acted in this respect completely independently of government, and in his independent public interest capacity."

Liberal Democrat leader Sir Menzies Campbell told BBC Two's Newsnight that "the attorney general acts in the public interest, and in particular, he's got an interest to ensure that no possible prosecution is prejudiced or that no possible defence to a prosecution is prejudiced".

He added: "I think what one might be able to infer from the fact that he felt it necessary to seek this injunction is that he at least contemplates the possibility that a prosecution of some kind will follow."