Coutts chief executive Peter Flavel has stepped down, saying that he bore “ultimate” responsibility for the bank’s treatment of former UK Independence party leader Nigel Farage.

The private bank and its owner, NatWest, have been engulfed in a crisis since Farage revealed last week that Coutts had closed his account in part because of his political views.

“In the handling of Mr Farage’s case we have fallen below the bank’s high standards of personal service,” Flavel said in a statement on Thursday. “As CEO of Coutts it is right that I bear ultimate responsibility for this, which is why I am stepping down.”

The revelation prompted a furious political backlash and this week cost NatWest chief executive Dame Alison Rose her job after she admitted to inaccurately briefing a BBC journalist over why Farage’s account was closed.

A 40-page dossier prepared for Coutts’s wealth reputational risk committee and obtained by Farage was scathing in its criticism of his worldview.

“Continuing to bank NF was [not] compatible with Coutts given his publicly-stated views that were at odds with our position as an inclusive organisation,” one memo read.

It also stated that Farage used “extreme, hateful and emotive language . . . at best he is seen as xenophobic and pandering to racists”.

Flavel joined Coutts as chief executive in March 2016 after leading JPMorgan’s private wealth business in the Asia-Pacific region. Since taking over he had sought to modernise the image of the institution formerly known as the “Queen’s bank”.