Nigel Farage is former leader of the Brexit Party and the anti-immigration party UKIP
Nigel Farage is former leader of the Brexit Party and the anti-immigration party UKIP AFP

UK bank NatWest displayed "serious failings" in its treatment of the banking affairs of arch-Brexiteer Nigel Farage, an independent probe found Friday.

Farage -- ex-leader of the Brexit Party and the anti-immigration party UKIP -- complained earlier this year about the closure of his account with upmarket NatWest division Coutts, claiming he was removed for his political views.

NatWest appointed law firm Travers Smith to investigate the "debanking" controversy, which sparked the resignation of former chief executive Alison Rose in July.

Initial findings, published Friday alongside NatWest's quarterly results, found Rose made an "honest mistake" in discussing details of Farage's account with a BBC journalist -- which prompted her exit.

"She honestly, but incorrectly, believed that the client had publicly confirmed that he was a customer of Coutts," the report read.

However it also found that the closure of Farage's account was lawful because it was a commercial decision.

"Coutts considered its relationship with Mr Farage to be commercially unviable because it was significantly loss-making," the report added.

In response, Farage blasted the news as a "whitewash" and a "farce" in an interview with BBC radio.

NatWest chairman Howard Davies admitted the lender had made "serious failings" in the treatment of the politician.

"Although Travers Smith confirm the lawful basis for the exit decision, the findings set out clear shortcomings in how it was reached as well as failures in how we communicated with him and in relation to client confidentiality," said Davies.

"We apologise once again to Mr Farage for how he has been treated.

"His experience fell short of the standards that any customer should expect."

London's Financial Conduct Authority added Friday that the report "highlighted potential regulatory breaches and a number of areas for improvement".

Separately, NatWest revealed Friday that third-quarter net profit more than quadrupled on rising interest rates.

Profit after taxation leapt to GBP866 million ($1.05 billion) in the three months to September from the same part of last year.

Revenue increased eight percent to GBP3.5 billion, boosted by a series of interest-rate hikes from the Bank of England.

The lender was lifted also by slightly lower provisions for loan defaults.

"Today's third-quarter results show that NatWest is a strong bank which is performing well, generating sustainable profits and returns," said chief executive Paul Thwaite, who replaced Rose in July.

"Credit losses and impairments remain low and we are ready and able to stand by our customers and businesses through the current economic uncertainty."

Some of NatWest's key UK rivals have faced increasing bad debt provisions, as they set aside money for loans turning sour in a cost-of-living crisis.

The BoE last month left its key interest rate unchanged at 5.25 percent, snapping a series of 14 straight hikes aimed at taming elevated inflation.

Those hikes have prompted UK retail banks to lift their own rates on loan products including mortgages, worsening a cost-of-living squeeze.