Unsuspecting guests at hotels in Glasgow were duped into revealing their bank details by fraudsters posing as hotel workers.
Police believe the scam is linked to a spate of incidents across the city centre.
Organised criminal gangs are using the new telephone scam to make bank customers reveal their card details.
Victims of the scam are called in their hotel room by someone claiming to be a member of staff from reception.
The caller tricks them into disclosing private financial information.
Police today warned people to be on guard and to never reveal card PIN numbers, bank or personal financial details - especially over the phone.
Chief Inspector Alan Porte, area commander for Glasgow city centre, said: "This scam involves hotel customers being called in their room by a criminal posing as someone from the hotel's reception desk.
"They tell the victim that there has been a problem with their credit or debit card and they need to check the card details. The victim then gives their bank details over the phone."
The conmen target people in hotels by duping them into handing over their bank card details, which can then be used to empty their bank account.
Mr Porte confirmed there has been reports of this scam - known as "phone phishing" - in the last two weeks in Glasgow city centre.
The senior officer added: "I would like to reinforce the message to the public to be vigilant about approaches from people, and never give over bank cards or give out PIN numbers.
"If you receive a call like this while staying in a hotel, I would advise you go down to reception and ask a member of staff in person.
"Never give your bank details out over the phone."
Police also want to hear from anyone who believes they may have been targeted by fraudsters.
Anyone concerned about a possible bank card scam is asked to contact Police Scotland on 101.