Last night, BBC Watchdog discussed how we deal with financial crime and why we block or close some accounts. I wanted to share some more details about how we approach this and be as transparent as we can.

Blocking accounts is a legal requirement, and helps protect you from crime

As a regulated bank, we have a legal duty to detect and prevent financial crime . We take our banking licence and the laws that come with it incredibly seriously, and our financial crime team has become known for its stand-out work in this area.

We’ve been able to return millions of pounds to victims of fraud in this way - work that I’m very proud of.

We block accounts when we detect suspicious activity

To detect financial crime, we have a set of automated rules that flag any activity that might be suspicious, and sometimes block the account. We aim to have a person review the account within 10 minutes (night or day) and, if we discover that it’s not suspicious, we immediately reactivate the account.

This only happens very rarely, and most customers will never even know it’s happening.

If the account activity does seem suspicious, we’re obliged to report it to the National Crime Agency and wait for their response before closing the account.

Sometimes, the evidence is very clear. We might receive a report from the police or another bank that confirms the money has come from authorised push payment fraud . Confirmed criminals will sometimes even take to social media to pressure our support team to release their money.

Other times, it’s not clear-cut, and we’ll ask customers to explain where the money has come from. We then need to make a judgment call based on the evidence in front of us. We won’t always get this right, and I wholeheartedly apologise to any legitimate customers who’ve been left out of pocket for a period of time. We’re continually working to minimise this, and we need to balance it with combating money laundering and financial crime, including £1.2bn of UK bank fraud every year .

We’re not allowed to say why we’ve blocked an account

Somewhat frustratingly, we’re not allowed to say why we’ve blocked an account, to either the customer or the press. This regulation is designed to protect ongoing law enforcement investigations. It’s a legal offence called “tipping off”.

Because of this, we can’t comment on the specific cases featured in the show. Instead, we gave a statement to the BBC to explain our position and we’ve included this below.

When we do have to close an account, we aim to return any money as soon as we can

When we’ve reported an account and decide to close it because we suspect there’s financial crime, there are a few things we have to do next. We either have to return the money to the bank it came from, send the money to law enforcement, hold it, or return it to the customer.

When we can return the money to the customer, we let them know it takes between 2-4 weeks to get it back (while we work on fulfilling our other legal requirements, like reporting what’s happened to the right places). On average it takes us 2.7 weeks. And when this very rarely takes longer than 4 weeks, it’s usually because of external investigations that are outside of our control.

We know that 2.7 weeks is still a long time for anyone to be without money, and we’re working hard to make this shorter.

When people can’t access money, we try to help as much as we can

If a customer tells us they’re struggling financially because they can’t access money, we’ll sometimes let them know about charities that can offer advice and support. This is a relatively common thing banks do in this situation to try and help.

When we’ve directed people to a food bank (which I believe we’ve only done on very few occasions) our customer service staff were genuinely trying to be helpful. The advice came from a good place, but I’m sorry if that caused any upset or distress. I acknowledge our communication has been poor in some of these cases. We’ve rolled out new guidance for staff to make sure we only sign-post people to charities or help when it’s appropriate for their circumstances.

We’re no strangers to holding our hands up and admitting fault - transparency is one of our core values. We’re not perfect and there’s always more we could be doing to be better. But, at the heart of this issue is the work we do to prevent criminals using our financial system for gain. At the same time, we must make sure we keep any negative impact on our customers to a minimum.

Here’s the full statement we provided to the BBC:

“Typically, if we discover that activity is not suspicious, an account that has been frozen is reactivated in 10 minutes. We have robust processes and controls in place to flag any unusual activity in Monzo accounts.

Crucially, no conclusions can be drawn based on a bank refunding those whose accounts have been closed. It does not mean they have been treated unfairly. Without context, which we are prohibited from sharing by law, it is incorrect to reach a conclusion about why accounts have been frozen or closed.

Our customers have consistently praised our award-winning customer service. Feedback from customers is incredibly important and we're always working to do better but in these cases, we have acted in line with our legal and regulatory obligations.”