Banking giant HSBC was accused of racism this week after it moved to close the accounts of several Muslim organizations across the UK.
Finsbury Park Mosque in the north of London claimed that it had received a letter from HSBC on July 22 giving notice of the closure explaining that it would be outside the bank's "risk appetite" if it were to continue providing services to it.
The mosque reacted to the letter this week by questioning the motives behind the closure, telling the BBC that the only reason this has happened is because of an Islamophobic campaign targeting Muslim charities in the UK. The mosque has been busy trying to repair its image after a link to radical Islamic cleric Abu Hamza ten years ago. Hamza was convicted on 11 terrorism charges in the U.S. last month.
The BBC also reported that HSBC had closed the account of the Ummah Welfare trust, based in the north of England, which said the bank had targeted it due to its continuing work in Gaza.
Read MoreThe 'dark pool'debate—here's what you need to know
HSBC, who promotes itself as a global bank with roots firmly in the U.K., is still reeling from a fine of $1.92 billion in late 2012 after it was accused of failing to prevent the laundering of criminal cash.
The bank strongly refuted claims of racism and said that, more generally, the decisions to end customer relationships are not taken lightly.
"(They) are absolutely not based on the race or religion of a customer. Discrimination against customers on grounds of race or religion is immoral, unacceptable and illegal," a spokesperson said in a statement.
"We take our responsibilities to customers and society very seriously, and remain committed to supporting our small business and charity customers."
Rowan Bosworth-Davies, a financial crime consultant and former detective at London's Metropolitan Police fraud department, says that his own research has found that banks can behave like this whenever they like without having to give reasons.
"I have always wondered about the legitimacy of these kind of dealings," he told CNBC via email. "Other banks have closed accounts in the past belonging to groups or individuals who might conceivably bring them into conflict with the regulators."
HSBC added that it had entered into a deferred prosecution agreement with U.S. authorities - effectively placing the bank into a probationary period - and was currently assessing its business practices. As part of this assessment it said it had exited relationships with business and personal customers in over 70 countries. It added that charities were not exempt exception to this global review.
Read MoreBNPParibas posts $5.7B loss after record US fine
In late June, French lender BNP Paribas was hit with a huge $9 billion settlement with U.S. authorities for breaching sanctions against dealing with Sudan, Cuba and Iran.
Prosecutors had accused BNP Paribas of processing billions of dollars through the U.S. financial system on behalf of the Sudanese, and others barred because of human rights abuses, support for terrorists and other security concerns.
Chris Skinner, CEO of Balatro and director of the Financial Services Club said that banks are now weighing up the benefits of providing accounts for these clients against the potential costs for risk assessment and telling some of them to just "go away."
"They are taking a very hard line," he told CNBC via telephone. Previously banks would have had an "accept all" approach, he added, but were now busy throwing customers off of their network and that he expected more banks to follow suit.