Police are investigating reports of media outlets hiring experts to crack the security passwords on stolen mobile phones, amid fears they could be "the tip of the iceberg".
Giving evidence to the Leveson inquiry today, deputy Metropolitan police assistant commissioner Sue Akers said she was trying to establish if the stolen mobiles were isolated incidents or part of a structured programme.
Police started investigating theft when they realised some of the News International material being poured over in Operation Tuleta came from stolen phones.
One of the mobile phone thefts took place in Manchester and another in south-west London.
So far, six people have been arrested by Operation Tuleta under the Computer Misuse Act or on suspicion of handling stolen goods.
Akers painted a staggering picture of the scale of the investigation.
Police are looking at eight to 12 terabytes of data. To give a sense of scale, if put in the form of paperback books it would equate to between 25 to 42 times the height of Everest.
Some 2,615 people have been informed they may have been phone-hacked, while the police believe 702 "are likely to have been victims".
There are 101 separate allegations of data intrusion, including phone-hacking, computer hacking and improper access to medical or bank records.
The courtroom sat in silence as Akers outlined the scale of the investigation.
She warned the Sun newspaper had held back on giving the police evidence after it was criticised for hanging its journalists out to dry.
Despite a tense and uneasy relationship, the work between the Sun and the Methas continued, however.