'I am accountable and could have done more,' says Met police's John Yates

Scotland Yard and the Crown Prosecution Service will be severely criticised for their handling of the phone-hacking investigation later this month when an influential parliamentary committee publishes a damning report into the affair. The Observer understands that the culture, media and sport select committee, which originally investigated the scandal, is to issue a follow-up report that is expected to be scathing of senior figures in both organisations. The most savage criticism will be for John Yates, the Met's assistant commissioner, who investigated claims that phone hacking on the paper was widespread following the original inquiry. Yates voiced his "extreme regret" that he did not reopen police inquiries into phone hacking two years ago, despite fresh claims that thousands had been targeted. "I am accountable and it happened on my watch and it's clear I could have done more," he told a Sunday newspaper. "I have regrettably said the initial inquiry was a success. Clearly now that looks very different." The new report is also expected to criticise the former director of public prosecutions, Lord (Ken) Macdonald, who advised the Yard on the scope of its original investigation. Macdonald was head of the CPS during the initial inquiries in 2005 and 2006, when critics maintain it was aware of the true scale of the phone hacking. The committee is likely to claim the CPS simply "rubber-stamped" the Yard's request to restrict the remit of its original investigation, which was confined to a handful of victims. The CPS has defended its decision, saying it was standard procedure in complex cases to limit the scope. Macdonald's successor, Keir Starmer, will also come under fire, the Observer understands. One MP said: "Yates was tackled very aggressively by the select committee over the failures of the police investigation, including the lamentable performance in contacting victims. The report will undoubtedly be scathing about his actions and sceptical of the motives for the police in trying to close the inquiry as soon as they could." To comment on this story or any other about phone hacking from 9am on Sunday, go to our open thread • This article was amended on 11 July 2011. A sentence incorrectly stating that Lord Macdonald is advising News International on civil phone-hacking claims was removed.