Online criminals are sending fake invoices to East Midlands businesses in an attempt to scam them out of money.
The East Midlands Special Operations Unit (EMSOU) says the region has seen an increase in Invoice Fraud cases during recent months.
The scams attempt to trick companies into paying out on what looks like a legitimate bill addressed to them.
In its latest Cyber and Fraud Protect bulletin, the EMSOU says:
"EMSOU has noted an increase in Invoice Fraud. Essentially, this is when someone requests services from a legitimate organisation and then receives an invoice.
"Further down the line, the victim then receives further demands for payment.
"This is because a criminal has either intercepted communications between the victim and the vendor and is attempting to exploit it for personal gain, or because they have assumed that you have – at some point – taken advantage of the vendor’s services."
To combat the problem, EMSOU has issued guidance on how firms can protect themselves against Invoice Fraud.
It says businesses should include a message at the end of invoices that encourage the recipient to check the invoice is legit.
Officers suggest a message similar to this:
The EMSOU said: "We encourage every organisation to print a message like this on the bottom of every invoice sent.
"The key point is to encourage customers to use the contact details shown in the initial / original invoice to make contact, otherwise they could be calling the fraudsters."
Last year, research suggested one in seven small-to-medium sized firms in Britain had fallen victim to an invoice scam over a 12-month period.
Barclays said its study found more than a quarter of invoice scams resulted in losses of more than £5,000 - and that only 25% of employees said they would double-check an invoice before paying it.
You can report a fraud to Action Fraud by using its online fraud reporting tool, or by calling 0300 123 2040.