A judge has rejected a BBC request to disclose the reasons for an injunction which blocked a report concerning the cash-for-honours police investigation.
Lord Levy has denied any wrong-doing
Although the injunction has since been lifted, three key paragraphs - relating to arguments for it put by the attorney general and police - remain in force.
The story was about a document raising an aide's concern about Lord Levy's role in drawing up the Honours List.
Mrs Justice Swift refused permission for a BBC appeal against the ruling.
The BBC's story was that Ruth Turner, director of government relations, had said, in the document, that she was concerned that an account given to her by Lord Levy of his role in drawing up the Honours List had been untrue.
The BBC has not seen the document containing her concerns but has been told about it by more than one source.
The judge confirmed that Jonathan Powell, the prime minister's chief of staff, was the addressee of the document, although it is not known whether it was sent or received.
Mrs Justice Swift's full statement to the court was: "The BBC restrained from publishing a story about the content of a document written by Ms Ruth Turner, Director of Government Communication at Number 10 Downing Street.
"The addressee was Mr Jonathan Powell, chief of staff at Downing Street. This document is alleged directly or inferentially to suggest that Lord Levy, one of the persons under investigation, had sought to influence what Ms Turner said to the police.
"During the course of the argument on Friday material was deployed by leading counsel through the Attorney General which went further than the subject matter of the document at issue.
"Some of that material was referred to by the judge in his judgement. It originated from the police officers responsible for conducting the investigation.
"I am satisfied that it is necessary in the interests of justice for those parts of Friday's proceedings which contain reference to the additional material... To remain private.
"I am satisfied also, that there is confidential information contained within that material and that publicity would damage confidentiality of that inquiry."
In response to reports earlier this week, Neil O'May, from Lord Levy's solicitors Bindman & Partners, said he "categorically denies any wrong-doing whatsoever".
Mr O'May added that the "current round" of media reporting was "partial, contradictory, confused and inaccurate" and could be perceived as a "media-style trial".
Meanwhile, Scotland Yard has confirmed that Met Police chief Sir Ian Blair attended a dinner with Lord Levy, who is currently on police bail.
Scotland Yard said Sir Ian and Lord Levy were at the "top table" of the Community Security Trust dinner on February 26.
"The commissioner did not discuss details of the investigation into alleged abuse of honours with Lord Levy."
There were more than 1,200 guests at the dinner.
"[Sir Ian] was aware that Lord Levy would be present and acted in accordance with police instructions about meeting people on police bail, informing an appropriate senior officer both before and after the event.
"The commissioner was one of 18 guests on the 'top table' along with Lord Levy although at [a police] request they were not seated close to each other," police said.
The cash-for-honours probe began a year ago. Police are investigating allegations that honours were exchanged for loans to the Labour Party.
The probe switched its focus recently from the question of cash-for-peerages to allegations of a cover-up.
All involved in the inquiry deny any wrongdoing.