Downing Street aide Ruth Turner wrote that Labour's chief fundraiser Lord Levy asked her to "lie" for him in the cash-for-honours investigation, a court was told.

Ms Turner, one of Tony Blair's closest aides, apparently made the claim in a document addressed to the Prime Minister's chief of staff, Jonathan Powell.

It emerged yesterday in court as the BBC was finally allowed to say why the organisation had been banned from reporting the document.

Reports previously suggested that Ms Turner felt Lord Levy had tried to shape her evidence to Scotland Yard detectives.

But Mr Justice Wilkie, who originally granted the injunction against the BBC, appeared to say that it went further.

He said: "There is a substantial element of truth in what the intended BBC broadcast was to say.

"There is a document addressed to Jonathan Powell in the course of which she (Ruth Turner) alleges Lord Levy had asked her to lie for him."

The disclosure came as three of the country's most senior judges lifted the final gag on the BBC in reporting the cash-for-honours probe.

The Court of Appeal also refused Attorney General Lord Goldsmith's application to take the case to the House of Lords or stay the decision until he could approach the Law Lords directly.

Master of the Rolls Sir Anthony Clarke said the police requested the order because they feared that their inquiry into an alleged cover-up over the inquiry could be prejudiced.

Scotland Yard detectives were concerned the document written by Ms Turner, director of government relations at Number 10, could fall into the hands of people police might wish to interview and use it to work out a response beforehand.

Sir Anthony, with Lord Justice Dyson and Lord Justice Thomas, lifted the ban on the BBC from reporting proceedings.