The former UKIP and Brexit Party leader claimed the elite bank took the action because his views did not align with the firm's "values".

But other media reports suggested it was down to his finances not reaching the company's threshold.

Earlier this week, Mr Farage claimed to have a 40-page document that proved Coutts "exited" him because he was regarded as "xenophobic and racist" and a former "fascist".

But Coutts hit back, saying it did not close accounts "solely on the basis of legally held political and personal views".

Now, after weeks of the row playing out in public, the chief executive of the Natwest Group, Alison Rose, has apologised for "deeply inappropriate comments" made about him in documents prepared for the company's wealth committee.

In a letter to him, seen by Sky News, she insisted the remarks did "not reflect the view of the bank", adding: "I believe very strongly that freedom of expression and access to banking are fundamental to our society and it is absolutely not our policy to exit a customer on the basis of legally held political and personal views."

Mr Farage posted a video on Twitter, saying he was "going to think and absorb this over the course of the next hour or so".

The apology came as the Treasury announced new stricter measures on banks closing accounts to protect freedom of expression.

The government said the organisations will now have to inform customers of the reasons why they are closing accounts, and extend the notice period from 30 days to 90 - giving customers more time to challenge the decision or find a new bank.

Economic Secretary to the Treasury, Andrew Griffith, said: "Freedom of speech is a cornerstone of our democracy, and it must be respected by all institutions.

"Banks occupy a privileged place in society, and it is right that we fairly balance the rights of banks to act in their commercial interest, with the right for everyone to express themselves freely."

Read more:
What happened to Nigel Farage's bank account?
Are banks allowed to close accounts?

In her letter, Ms Rose said she "fully understands" both Mr Farage's and the public's concerns that the processes for bank account closures were not "sufficiently transparent", adding: "Customers have a right to expect their bank to make consistent decisions against publicly available criteria and those decisions should be communicated clearly and openly with them, within the constraints imposed by the law."

She agreed that "sector-wide change" was needed but, following the incident with Mr Farage and Coutts, she would now commission a full review of the bank's processes "to ensure we provide better, clearer and more consistent experience for customers in the future".

In a further statement released after Sky News broke the story of the letter, Ms Rose reiterated her apology, but added: "It is not our policy to exit a customer on the basis of legally held political and personal views.

"Decisions to close an account are not taken lightly and involve a number of factors including commercial viability, reputational considerations, and legal and regulatory requirements."

The bank has now offered "alternative banking arrangements" at NatWest