1) Always confirm invoice account details directly with your supplier, using established contact details, BEFORE making any payment, even if you have paid them before. Avoid using the contact details in an email as you could end up speaking to a fraudster.
2) Establish at least two designated points of contact with all your regular suppliers. And do this over the phone. This will make it easy to check any change of bank account or payment arrangements directly with them.
3) Carefully scrutinise all invoices you receive. Look out for spelling errors or slight changes to email addresses.
4) Educate any employees responsible for processing supplier invoices about this type of invoice fraud.