PRESS ASSOCIATION -- Cabinet Secretary Sir Gus O'Donnell warned ex-PM Gordon Brown that a phone hacking inquiry would be open to legal challenge, documents released by the Cabinet Office have revealed.
He also advised Mr Brown that launching a probe just two months before the General Election would "inevitably raise questions over the motivation and urgency of an inquiry".
But officials insisted the final decision over whether an investigation should have been launched rested with the then Prime Minister.
The documents were released following Mr Brown's claims that he had been talked out of launching a judicial inquiry by Sir Gus.
Mr Brown insisted he wanted to take action following a report by the Culture, Media and Sport Committee in February last year that had suggested the number of hacking victims was more than the handful originally claimed.
In a seven-page briefing note, the Cabinet Secretary warned that the public interest test in holding a public inquiry could have been outweighed by the fact that the committee believed it was unlikely the practice of phone hacking was continuing. He also pointed out the time elapsed since the original phone-hacking scandal in 2007 meant it "may make it unlikely" that more information would be discovered.
That would mean the inquiry would have been targeted only at the News of the World and "could be deemed to be politically-motivated", making the possibility of a successful judicial review "more likely".
Sir Gus set out the key characteristics of previous public inquiries, which included large-scale loss of life, serious health and safety issues, and failures in regulation. He also raised concerns about the cost of an inquiry and the precedent it would set.
But at a press conference, Deputy Prime Minister Nick Clegg questioned whether it was believable that Mr Brown had been "hamstrung by dastardly officials".
He said: "I sense the whiff of rewriting history, to be honest. He was prime minister, he was a very powerful chancellor for many years before that, he was at the very apex of politics for 13 years. Are we really supposed to believe that for 13 years he was hamstrung by dastardly officials who stopped him doing that?"