The police chief who headed Scotland Yard's inquiry into phone-hacking dined with the News of the World at the height of his criminal investigation into the newspaper.
The sensitively timed meeting between then Assistant Commissioner Andy Hayman and the NOTW was left off lists of contacts between senior officers and the paper's owner sent to the Metropolitan Police Authority. Its disclosure in a Freedom of Information request prompted claims that the force had an unduly "cosy relationship" with Rupert Murdoch's print empire News International (NI).
Mr Hayman enjoyed three lunches and two dinners with the NOTW in the two years ending in 2007. One dinner was on 25 April 2006, four months after the Royal Family alerted the Yard to the loss of personal data about Princes William and Harry and four months before anti-terrorist police raided the offices of the NOTW's royal editor Clive Goodman and its private investigator Glenn Mulcaire, in August 2006.
Mr Hayman, who joined the NOTW's sister paper The Times as a columnist after retirement, said he could not remember with whom, or in what circumstances, he had the dinner. He said he could not comment without knowing the details.
His investigation into the NOTW's suspected hacking of the phones of celebrities and politicians was scorned by MPs for failing to interview figures including chief reporter Neville Thurlbeck. Sue Akers, who is leading a new police inquiry, reportedly told one alleged victim, John Prescott, she was "not satisfied" with the original inquiry.
Last night the Met issued a statement saying: "Andy Hayman was the Metropolitan Police and Acpo lead for counter-terrorism, and this area of high public interest and concern was his main purpose for meeting with the media. All hospitality must be recorded and these meetings with NI were recorded in the hospitality register."
The MP Tom Watson said: "It is utterly unbelievable a senior investigating officer could think it appropriate to socialise with executives from an organisation he was investigating. We need to know who knew, who was there and what was discussed."
Two months ago, the Met disclosed that Commissioner Sir Paul Stephenson had dined with the NOTW seven times between 2006 and 2010, during which time his force turned down calls for the hacking investigation to be reopened. This week it disclosed a further 20 meetings with NI, including a lunch Mr Hayman enjoyed at The Times in February 2006, while he was investigating its sister title.
Neither list disclosed his five NOTW engagements: two dinners in November 2005 and April 2006, and three lunches in March, September and November 2007. Acting Commissioner Tim Goodwin described the failure to list them as "an oversight".
Liberal Democrat MPA member Dee Doocey said: "It is extraordinary that when serious allegations about illegal phone-hacking relating to the News of the World were still unresolved, the Commissioner and senior officers thought it was acceptable to devote so much time networking with senior executives of News International. I have real concerns about the appropriateness of such a cosy relationship."
How Andy Hayman ended up on Murdoch's payroll
Andy Hayman took charge of the phone hacking investigation in December 2005 because the publication of personal details about the Royals had caused security concerns.
The Assistant Commissioner was the UK's top counter-terrorism officer. His inquiry led to the conviction of Glenn Mulcaire and Clive Goodman – which he said sent a strong message to journalists.
But his investigation was criticised by the Commons Culture, Media and Sport Committee for not going far enough, failing to look into Mr Mulcaire's contract and an emailed transcript marked "for Neville". The MPs said: "The Metropolitan Police's reasons for not doing so seem to us to be inadequate."
Mr Hayman resigned in 2007, complaining about "unfounded allegations" over his expenses and an alleged relationship with a junior officer. He became a columnist on The Times, the NOTW's sister title.