Chancellor Jeremy Hunt has asked the City watchdog to look into the extent of de-banking, as he said the practice poses a “threat” to free speech.
It comes as banks face widespread reforms over account closures, after the Nigel Farage row that last week led to the resignation of the top bosses at Natwest and Coutts.
The former Ukip leader said his bank account was unfairly shut down by Coutts, owned by Natwest Group, because it did not agree with his political views.
Mr Farage’s campaign against account closures has received support from ministers, with Mr Hunt expressing concern over how many people are affected.
The Chancellor has asked the Financial Conduct Authority to look into the issue and report back to him next month.
He told broadcasters on Thursday: “I’m worried that it may exist more than we had thought.
“And the reason I’m worried is because free speech is a fundamental human right. And you can agree or disagree with Nigel Farage but everyone wants to be able to express their opinions.
“But in today’s society you need a bank account to function and so a threat to be de-banked, as the word is now widely used, is a threat to your right to express your opinions.
“So we have regulations, I think it’s regulation 18 of the payment accounts regulations, that ban this so-called de-banking of people for their political views.
“I’ve written to the regulator, which is the Financial Conduct Authority. They have the right to fine banks very large sums of money if they find this practice is widespread.
“I want to know if it is and I want to know what they’re doing about it and they said they’ll get back to me by September.”
Mr Farage responded by tweeting: “The Chancellor has written to the FCA about my case and the issue of de-banking. Thank you @Jeremy_Hunt.”
The ex-MEP this week said Coutts has offered to reinstate his personal and business accounts, while he is also seeking compensation from the private bank.
Natwest has announced an independent review, with lawyers looking at the closure of Mr Farage’s account and other instances of de-banking by Coutts.
Natwest’s Dame Alison Rose resigned as chief executive after acknowledging a “serious error of judgment” by discussing with a BBC journalist Mr Farage’s relationship with Coutts.
Press Association – Sophie Wingate