The issue has now escalated with the bank's CEO, Dame Alison Rose, admitting to a "serious error" in her response to questions from the BBC regarding Farage's relationship with the bank.

Dame Alison said she was wrong to have responded to questions from the BBC about Farage's account being closed and apologized for any personal hurt caused to the former UKIP leader.

The controversy began when the BBC reported that Farage's account was closed because he no longer met the wealth threshold for Coutts.

However, the BBC later apologized for its inaccurate report and Farage produced a Coutts report which indicated that his political views were also considered in the decision to close his account.

Farage has called for Dame Alison to resign, and several Tory MPs, including former cabinet minister David Davis, have also joined in the chorus for her to step down.

The ex-UKIP leader said that Dame Alison should take responsibility for her actions and that NatWest should conduct an independent review into the matter.

NatWest has faced mounting pressure to explain how information about Farage's account closure was disclosed.

In her first admission of involvement, Dame Alison said that she had confirmed to the BBC's business editor, Simon Jack, that Farage was a Coutts customer and had been offered a NatWest bank account.

She said she believed this was public knowledge.

Dame Alison also acknowledged that she had not revealed any personal financial information about Farage.

However, when Coutts decided to close Farage's account, the bank did not give him a reason.

Farage subsequently obtained a 40-page document that flagged concerns about his suitability as a Coutts customer, including his "publicly stated views." The document also questioned the reputational risk of having Farage as a client and stated that to have him as a customer was not consistent with Coutts' "position as an inclusive organization." NatWest chairman Howard Davies said that Dame Alison's response to the BBC's questions was a Nigel Farage, the leader of the UK Independence Party (UKIP), has accused Dame Alison Cox, the chief executive officer of the Royal Bank of Scotland (RBS) and NatWest, of breaking client confidentiality rules.

In a tweet, Mr Farage claimed that Dame Alison was "unfit to be CEO of NatWest Group".

The BBC has declined to comment on the matter.

It is not clear what specific information Mr Farage is referring to or what client confidentiality rules Dame Alison is believed to have breached.

However, the accusation comes at a sensitive time for RBS and NatWest, which are both still recovering from the financial crisis of 2008.

In 2019, RBS was fined £42.4 million by the Financial Conduct Authority (FCA) for failing to properly handle a large number of customer complaints.

The bank was also found to have misled the FCA in relation to its treatment of small business customers.

RBS has since apologised for its actions and has made efforts to improve its handling of customer complaints.

NatWest, which is part of the RBS group, has also faced criticism in recent years.

In 2021, the bank was found to have breached money laundering regulations after failing to properly verify the identity of customers making large transactions.

The bank was fined £7.7 million by the FCA and has since committed to making improvements to its anti-money laundering processes.

In light of these recent controversies, the accusation made by Mr Farage against Dame Alison is likely to attract scrutiny.

It remains to be seen what further information will emerge about the situation and what actions, if any, will be taken as a result.