Scotland Yard's injunction against the BBC, preventing it from broadcasting new details in the cash-for-honours investigation, is expected to be lifted this week when a team of detectives led by the assistant commissioner of the Metropolitan Police, John Yates, has completed a new focus of its inquiry.
The BBC is understood to have intended to broadcast the identity of a person interviewed by the inquiry team who was subsequently ordered by police to respect a week-long news blackout.
New information given during that interview is being followed up by police and, during the two-hour injunction hearing at the High Court on Friday, they are said to have been determined their inquiry should not be derailed by disclosure by the BBC.
The piece was due to be aired on the 10 O'Clock News.
The same order was given by Scotland Yard when they last interviewed Tony Blair in Downing Street on January 26. The prime minister appeared in the Commons, giving no indication that he had just been interviewed by police for a second time. Downing Street later said the PM could not reveal details of the interview because of a news blackout ordered by Scotland Yard.
The current injunction, obtained by the attorney-general, Lord Goldsmith, on Friday night, prevented the BBC's political editor Nick Robinson from adding any new detail on the cash-for-honours inquiry.
The office of the attorney-general said the injunction was made 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".
BBC lawyers are understood to be preparing an urgent appeal against the injunction ruling and will present their case to the High Court tomorrow.
In a brief statement on the matter, given under the terms of the injunction, the BBC insisted that their report was a "legitimate matter of public interest".
The determination of the Metropolitan Police to protect what officers see as valuable evidence, and the potential for further evidence gathering, has led to speculation that a prosecution will now result from the Scotland Yard inquiry that began in March of last year.
Speaking this weekend from his party's spring conference in Harrogate, the Liberal Democrat leader Sir Menzies Campbell said: "I think that what we might be able to infer from the fact that the attorney-general felt it necessary to seek this injunction is that he at least contemplates the possibility that a prosecution of some kind will now follow."
Angus MacNeil, the Scottish National Party MP whose complaint triggered the initial investigation, said the state of the Met's inquiry now pointed to Labour facing "an unprecedented political crisis".
He added: "The gravity of this investigation is clear for all to see. It would appear that the police may have significant information that they don't want to made public at this stage."
So far, four people have been arrested in connection with the honours investigation: the prime minister's chief fund-raiser Lord Levy; Downing Street aide Ruth Turner; a Labour donor, Sir Christopher Evans, and Des Smith, a former head teacher and education adviser.
The prime minister has been interviewed twice, both times as a potential witness, not as a suspect.
One line of inquiry it is believed the police are pursuing is an attempt to verify a sequence of emails alleged to emanate from within Downing Street that point to worries over the inquiry and how it could damage the government's reputation.
It is the alleged existence of the emails which forced Yates's team to re-examine their entire case at the end of last year, and pursue the prospect that key individuals could be suspected of perverting the course of justice in an orchestrated cover-up.
Despite the lengthy inquiry, during which all those who were members of Blair's Cabinet in the run-up to the 2005 general election have been questioned, no-one has yet been charged. Downing Street has continued to insist that no law has been broken.
