It had been thought the Murdoch group had requested that emails be deleted on nine occasions, but a company hired to delete the messages yesterday said that it had done so on four more occasions.
The extra deletions, requested between December 2009 and June this year, included emails from the inbox of a user who had not accessed his account for eight years.
The deletions to the eight-year-old account were carried out a few months after the phone hacking scandal reignited amid reports that hacking at the News of the World was more prevalent than previously thought.
Some deletion requests related to two personal folders and a tranche of “bad or corrupted” files.
Many of the other deletions, performed by HCL Technologies, were carried out before News International ordered its staff in an internal memo to stop deleting emails earlier this year.