Sky News reported that a current suspect has turned whistleblower, providing information on new potential victims and journalists who participated in the practice while chasing stories for tabloids.
Detectives working on Operation Weeting are now following up the information. It is thought some of the people whose phones may have been compromised have already had cases settled.
The informant is believed to have first-hand experience of hacking voicemails. Allegations are understood to relate to both News International and Mirror Group titles.
Earlier this week, journalists from Mirror Group titles were questioned for the first time as part of the investigation.
James Scott and Nick Buckley, the current editor and deputy editor of the Sunday People, have been arrested over allegations relating to their time at the Sunday Mirror.
Former Sunday Mirror editor and deputy editor Tina Weaver and Mark Thomas have also been questioned.