TalkTalk has moved to calm customers, claiming that a recent cyber attack on its system, "was not as bad as first thought".
The company claims the amount of financial data stolen in the breach was "materially lower" than previously anticipated.
It added that the attack was on its public-facing website and not on its core systems, although experts have warned up to four million customers may still be affected.
Dido Harding, CEO of TalkTalk told Sky News: "The financial information they have on its own is not enough for them to access your bank account."
She said the biggest source of risk was from criminals posing as bank staff in calls to unsuspecting customers.
"We now expect the amount of financial information that may have been accessed to be materially lower than initially believed and would on its own not enable a criminal to take money from your account," Harding added.
TalkTalk said the Metropolitan Police Cyber Crime Unit is continuing to investigate the incident alongside BAE's Applied Intelligence arm.