A few TalkTalk customers affected by one of the largest cyber-attacks in British history have claimed that money has been taken from their bank accounts. They have also accused the company of covering up the cyber-attack and not warning them about the breach soon enough.

TalkTalk customer Barbara Manley from Gravesend claims she had £9,000 stolen from her bank account. She told the BBC: "When I checked my bank statement I nearly died. [The hackers] had practically cleared my bank account out."

Manley received a call on October 18 from someone purporting to be from TalkTalk who knew all her personal details and managed to convince her to access her computer, Manley added. The call was made five days before TalkTalk announced that they had been hacked on October 22.

When they contacted the company about the missing money, TalkTalk reportedly only sent her a Freeview box, according to Manley's daughter Sarah.

Meanwhile, other customers vented their anger on social media also claiming that money has been withdrawn from their bank accounts. Hilary Foster, 43, said: "Thanks a bunch @talktalk_uk. Bank account cleared out because of your incompetence."

And Labour councillor Adrian Morris, who claims that he was hacked, accused the company of engaging in a "huge cover-up".

Thanks a bunch @TalkTalk_UK. Bank account cleared out because of your incompetence.

— Hilly (@HillyFoz) October 23, 2015

.@BBCBreakfast I was hacked morning Friday 16th. Called @TalkTalk_UK and they admitted hacking. There has been a huge cover-up

— Adrian Morris (@Adrian_Labour) October 24, 2015

The cyber-attack on TalkTalk could have affected all of the company's existing four million customers, but it was revealed last night that many more could be affected because previous customer details have also been stolen. The information that has been stolen includes dates of birth, telephone numbers and credit card and bank account details. Hackers can use the details to access bank accounts directly or to perpetrate identity fraud.

The revelation comes as the company's senior staff and management have been accused of ignoring warnings that its cyber security was inadequate, according to the Times. It has been claimed that a security consultant was "fobbed off" when he warned the company last September that it needed to encrypt material on its website.

TalkTalk's chief executive Dido Harding revealed that she had been contacted by the hackers who demanded some money. Scotland Yard's cybercrime unit, which is conducting an investigation into the attack alongside the National Crime Agency, is currently examining the email.

None has yet been identified as the perpetrators, but an Islamist group has claimed that it was responsible for the cyber-attack.