A drive to combat phone scammers has been launched after new figures showed a sharp rise in the amount of money lost to such fraud last year.
Financial Fraud Action UK (FFA UK), which represents banks, building societies and card companies, has launched a national advertising campaign to highlight the warning signs of a phone scam.
Its survey found the amount of money lost through these scams rose threefold to £23.9 million over the last year. It also found 58% of people received suspect calls about their banking details, a 17% rise on 12 months ago.
The police-backed campaign urges consumers never to give out their four-digit PIN over the phone, even if they think they are talking to bank staff or a police officer.
The FFA UK added that consumers should also never give out online passwords over the phone or agree to transfer money to a new account.
The financial services anti-fraud body said cold calling scams typically involve fraudsters deceiving victims into believing they are speaking to a police officer, a member of bank staff, or a representative of another trusted organisation, such as a computer company. This type of scam is also known as vishing.
Fraudsters will then try to get consumers to disclose passwords, transfer funds, or physically hand over money to someone who they say is a courier who will hold the cash for safekeeping.
Detective Chief Inspector Perry Stokes, head of the dedicated cheque and plastic crime unit, said: "Always be on your guard if you receive a cold call and are asked for personal or financial information, or to hand over your card or cash to someone.
"The bank or the police will never tell you to take such actions, so if you're asked it can only be a criminal attack."
The FFA UK adds that fraudsters may ask consumers to hang up and phone back, in a bid to win confidence. But this is a trick where the receiver is not put down at their end, leaving the line open, allowing the fraudster to simply restart the conservation when the consumer thinks a new call has been made.
Mr Stokes said if consumers are suspicious they should wait a full five minutes before calling back, call a friend first to make sure the line is free, or return the call from another phone.