TalkTalk customers are being targeted by an industrial-scale fraud network in India, according to whistleblowers who say they were among hundreds of staff hired to scam customers of the telecoms giant.
The scale of the criminal operation has been detailed by the three sources, who say they were employed by two front-companies set up by a gang of professional fraudsters.
The sources describe working in "call centres" in two Indian cities.
They say as many as 60 "employees" work in shifts in each office, phoning TalkTalk customers and duping them into giving access to their bank accounts.
The whistleblowers say they were given a script in which they were told to claim they were calling from TalkTalk.