Lord Prescott has said the press and the police are conspiring to hide the true extent of phone hacking and other illegal activity on Fleet Street.
Giving evidence to the Levesion inquiry into press ethics on Monday afternoon, the former deputy prime minister said Rupert Murdoch's News International had been let off the hook by the police.
"I think there is a conspiracy of silence to hide the facts and frankly I am stronger of that view in the last few months," he said.
In his written submission to the inquiry the Labour peer said: "It is absolutely clear to me that News Group were able to rely upon the inadequate police investigation to justify its (untrue) claim that the wrongdoing was limited to one person at the News of the World".
"For four years the MPS did not contradict any of these claims. In my view, the MPS has supported and assisted an organisation guilty of criminal behaviour and prioritised this over the fights of thousands of potential victims, including ordinary people whose privacy rights had been seriously violated and who knew nothing about it."
He added: "That is deeply shocking. The public duty of the MPS is to deal with crime and to protect victims of crime. In this case they appeared to have protected the perpetrators and misled the victims."
Wit the inquiry turning its attention to the relationship between journalists and the police, Metropolitan Police deputy assistant commissioner Sue Akers told the inquiry there was evidence suggesting "payments were being made to public officials who were in all areas of public life."
And she said The Sun newspaper had a "culture" of illegal payments to officials in all areas of public life.
Earlier this month Lord Prescott settled a claim against the Metropolitan Police for failing to warn phone hacking victims at the time of its original investigation into the NotW in 2006.
Later this week Lord Justice Leveson will hear from ex-Met commissioner Sir Paul Stephenson and his former assistant commissioner John Yates. Both men resigned over the phone hacking scandal.
Scotland Yard's original phone hacking inquiry resulted in the jailing of NotW royal editor Clive Goodman and private investigator Glenn Mulcaire in January 2007 after they admitted intercepting voicemail messages left on royal aides' phones.
However the Met was heavily criticised for limiting the scope of the investigation despite evidence from Mulcaire's notebooks that there could be thousands of hacking victims.
Mr Yates came under fire when he decided not to reopen the phone hacking inquiry after the Guardian published a story in 2009 revealing the illegal practice was far more widespread than previously believed.
Lord Leveson opened the session on Monday by attacking criticism of the inquiry.
"To publicly express concern about the existence of the inquiry when it is following its terms of reference is itself somewhat troubling," he said.
Meanwhile, singer Charlotte Church has settled her and her parents' phone-hacking damages action for £600,000 at the High Court. Church said she was "sickened and disgusted" by what she had discovered during her legal action against News International.