The News of the World has revealed that its computers have retained an archive of potentially damning emails, which hitherto it had claimed had been lost.

The millions of emails, amounting to half a terabyte of data, could expose executives and reporters involved in hacking the voicemail of public figures, including former deputy prime minister John Prescott, actor Sienna Miller, and former culture secretary Tessa Jowell.

The archived data is likely to include email exchanges between the most senior executives, including former editor Andy Coulson, who resigned as David Cameron's media adviser in January, as well as three former news editors – Ian Edmondson, Greg Miskiw, and Neville Thurlbeck – implicated in the affair by paperwork seized from Glenn Mulcaire, the private investigator who was on the News of the World's books. Edmondson was sacked in January. Miskiw and Thurlbeck were interviewed by police last autumn. No charge has been brought against any of them. Coulson and the three former news editors have all denied all involvement in criminal activity.

MPs on the home affairs select committee are likely on Tuesday to ask about the emails to John Yates, acting deputy commissioner of the Metropolitan police, when they question him over allegations he misled parliament in evidence he gave about the number of hacking victims originally identified by Scotland Yard. Yates told the committee six months ago the Met had only identified "10 to 12" individuals in a 2006 inquiry because the Crown Prosecution Service advised it to adopt a narrow legal definition of what constituted an offence. The Director of Public Prosecutions, Keir Starmer, has said that prosecuting counsel never adopted this narrow definition.

Several News of the World journalists have since been linked with phone hacking after victims began legal battles, raising questions about why Scotland Yard failed to conduct a more comprehensive inquiry. Only one reporter, former royal editor Clive Goodman, was convicted of a crime along with Mulcaire. Both men were sentenced to jail terms in January 2007.

No other reporters or executives were questioned by the initial police investigation and only Goodman's computer was seized. Only a series of high court cases brought by Sienna Miller and others have forced the Met to make available the material seized in a 2006 raid on Mulcaire's home, including his handwritten notes.

But the disclosure of internal emails from 2005 and 2006, when Mulcaire was at his most active, could reveal the full extent of phone-hacking at the paper and the identities of those involved.

In a ruling on Friday, a high court judge ordered the News of the World to make them available to the growing list of people suing the paper. Justice Geoffrey Vos, in charge of the hacking cases, ordered "rolling disclosure" to all claimants on Friday; hundreds of thousands of emails will now be handed over to alleged victims.

Parts of the first tranche, which contains up to 8,000 emails, will be passed to Sienna Miller's legal team in April. Lawyers acting for Sky Andrew, the football agent who is also suing the paper, will then receive all the News of the World emails in which Andrew is mentioned days later.

News Group told the high court it is close to completing a search through archived emails it claimed had been lost when transferred to India by its IT provider; its lawyers formally apologised to the court for previous claims the archive was not available. David Sherborne, for Sienna Miller, added that it remained 'mysterious' that the editor of the Scottish edition of the News of the World, Bob Bird, had given evidence on oath at the trial of Tommy Sheridan last year that the email archive had been lost on the way to India.

News Group also admitted a work computer used by Edmondson had been destroyed before Christmas. They agreed to provide detailed information about its destruction to computer specialists advising Sienna Miller.

Computers used by other News of the World journalists have also been replaced or disposed of, but News Group's lawyer, Anthony Hudson QC, said the data they contained had been copied and retained.

Sherborne told the high court on Friday that evidence of "a scheme" between News Group and Mulcaire to hack into Miller's mobile phone had been recovered by the Met during the raid on his home. It included an agreement to provide "daily transcripts" to the paper and monitor the activities of the actor's friends and associates, Sherborne said.

Further disclosures have been ordered by Vos. They include a copy of an email sent to Mulcaire asking him to target a "wish list" of 17 footballers.

News International maintains it will take tough action against any employee who is found guilty of wrongdoing.