Potential nuisance callers are able to buy sensitive personal data for as little as 4p per record, a consumer watchdog has warned.

An undercover Which? Money team found many of the 14 data-selling companies they investigated were willing to discuss buying personal information with the watchdog's fake pension firm, despite the business not being listed as a legitimate company.

One data-selling company offered to sell nearly 500,000 pieces of personal information on households with an income of £40,000 and over, including phone numbers and addresses, at just 4p each.

Another firm issued an invoice for 2,200 names and numbers of people with a household income of £35,000 and over at 66p per item.

While in most cases no personal data was exchanged during the investigation, one company sent a sample telephone list on which 13 out of 18 people were registered with the Telephone Preference Service (TPS), the register that allows people to opt-out of receiving unsolicited marketing calls.

Which? said basic research by the firms involved would have revealed that the watchdog's business was not listed at Companies House, FCA regulated or registered with the Information Commissioner's Office (ICO).

Only four of the 10 firms approached refused to deal with the fake pension company.

Which? did not buy any data from the other 10 firms they investigated.

In light of the investigation, the watchdog said many companies appeared to be in breach of the ICO's guidance that states consumers must give their consent for their details to be shared "knowingly and freely given, clear and specific".