An urgent protection warning has been issued to customers of HSBC, Lloyds Bank, Santander, TSB, Nationwide Building Society and Virgin Money.
It comes as a Which? investigation suggests the banks may be leaving customers vulnerable to fraudulent spoofing attempts. This is when a scammer attempts to impersonate legitimate companies - such as banks - to deceive victims. Scammers often forge the name and/or number that shows on an email or call from the legitimate site or retailer.
However, in a bid to made it more difficult for fraudster to impersonate them, companies can sig up to Ofcom's Do Not Originate (DNO) list. The regulator then shares this list with telecoms providers to help block potential scam calls and messages.
