The BBC story at the centre of an injunction focuses on an e-mail between two members of Tony Blair's inner circle, it has been revealed.
The Attorney General was granted an injunction after a two-hour hearing
The attorney general obtained an injunction against the BBC to stop it broadcasting an item on Friday night.
The details obtained by the BBC could have been central to the investigation into an alleged Downing Street cover-up over the cash-for-honours affair.
But the police were concerned that the BBC report could hamper the inquiry.
The investigation began a year ago into claims that honours were granted in exchange for loans to the Labour party.
It has recently expanded into an investigation into allegations of attempts to pervert the course of justice.