The calls ask people to log-on to a scam website that’s set up to steal their personal data.
The FOS said it does not “cold call’ consumers and would never ask to connect to their personal computer.
Consumers who receive suspicious phone calls from people who say they work at the ombudsman service are being advised to phone FOS directly on 0300 123 9 123.
The FOS said consumers should never provide personal details such as address and phone number, and banking or credit card information, unless certain the request is genuine.
No genuine banking firm ever asks for security information, such as internet or telephone banking passwords or log-on details, it warned.