Asked on Friday’s Today show on BBC Radio 4 whether other “big banks” should now be looked at, Augar said: “I think we need to find more [out]. It’s hard to answer that based on what we know.

“I’m not sure we’ve heard the full picture yet.”

Earlier this month, the BBC and the Financial Times reported that Mr Farage’s account was closed because his wealth did not reach the amount needed to keep a Coutts account open.

However, the documents obtained by Mr. Farage explicitly stated that he “complies with the CE [economic contribution] criteria for commercial retention”.

On Thursday, Natwest CEO Dame Alison Rose apologized for comments made in the document, calling them “deeply inappropriate.”

‘Just not in’

The BBC is also under pressure to apologize after publishing incorrect information about the closure of Mr Farage’s account.

A 4th of July story written by his business editor, Simon Jack, was headlined: “Nigel Farage Bank Account Closed For Falling Below Wealth Limit.”

He quoted “people familiar with the Coutts move” as saying the decision was “commercial”, but the corporation has since admitted that this was incorrect.

Speaking on Radio 4, Augar admitted that he, the BBC and “the media” had been all too eager to “bull up” the opening line about Farage’s bank balance.

And in light of the documents obtained by Mr Farage, Mr Augar said: “Banks have the right to vet their customers, they are looking to detect criminality, they are looking to detect corruption.

“None of that applies in this case as far as we know, this was just a simple ‘we don’t like opinions like this’ and it’s just not going on.

“Banks are not like any other business… they are a fundamental part of our structure. It is like a water or electricity company saying that we are not going to supply you because we do not like your political views. It can’t happen.

He added that Dame Alison may not be able to continue in her role depending “entirely on what she knew and when.”