The BBC was last night prevented from broadcasting a report into the cash-for-honours inquiry after the Attorney-General was granted an injunction.

A report had been compiled into why the Metropolitan Police had widened their inquiry from an investigation into claims about the sale of honours into one about alleged perversion of the course of justice. But the item for the Ten O’Clock News was blocked after government lawyers successfully applied for the gagging order.

It is understood that legal advisers to the police said that, had it been broadcast, the investigation into the alleged sale of peerages for party funds could have been scuppered.

Last night sources close to the inquiry refused to comment on whether the BBC story was accurate. One source said last night: “It was a story about why the police tactics changed.”

In December The Times revealed that the police had turned their attention towards an alleged attempt to cover up the sale of honours.

Lord Goldsmith, QC, the Attorney-General, applied for the broadcast to be prevented, saying that he was concerned that the report would prejudice the inquiry.

There was astonishment inside the BBC. An insider said that it had had “a good story but not something that would blow you out of the water”.

A spokesman for Lord Goldsmith said that the move was taken in response to a request from the Metropolitan Police, which has been engaged in a year-long investigation into claims that peerages were offered in return for financial support for political parties.

The spokesman said: “The application for an injunction was made by the Attorney-General this afternoon at the specific request of and in cooperation with the police, because of their concern that disclosure of certain information at this stage would impede their inquiries.

“The Attorney-General acted in this respect completely independently of Government and in his independent public interest capacity.”

Legal representatives from the Metropolitan Police were in meetings from midday as they sought a way of stopping the BBC’s story from being broadcast. It is believed that representatives of the Crown Prosecution Service were present.

Police and the CPS have previously been concerned by the leaks to the press.

The BBC said that the injunction had been granted after a two-hour hearing involving lawyers from the BBC and the Attorney-General’s office at the Royal Courts of Justice.

The injunction was sought at 6pm, and at 7pm government lawyers made their case to a judge in chambers. The ruling against the BBC was made about an hour before the story was to have been broken on BBC One’s Ten O’Clock News.

In a statement the BBC said that its report on cash-for-honours was a “legitimate matter of public interest“.

A Downing Street source said the first No 10 knew that an injunction had either been sought or granted was when they saw the Ten O’Clock News.

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