Consumer groups have called on the City watchdog to investigate credit-card firms amid fears they are using personal data to weed out “good” customers who use cards only for the perks.

Comparison sites report a marked increase in the number of borrowers with exemplary credit ratings and high incomes who are being turned down by card firms this year, since new rules on data sharing came into force in January.

Card firms can now exchange “behavioural” information about how customers use their cards, including whether they pay off their balances in full every month or use interest-free offers before dumping a card — making a loss for the provider.

Under rules set out by the UK Payments Association (formerly Apacs), this data should be used to prevent people falling into debt and not for commercial purposes. However, consumer groups fear it is being used to identify “unprofitable” borrowers.

Sunday Times reader Richard Phillips, 61, a QC from Leighton Buzzard in Bedfordshire, was rejected for the popular Abbey Zero card in June because he did not meet the provider’s “business criteria”, even though credit reference agencies class him as either a good or excellent credit risk. Experian gives him a near-perfect 901 out of 1,000. Phillips also earns a high six-figure salary and owns “substantial” assets. “I have never missed a payment in the past 40 years,” he said.

The case is doubly worrying because he applied for the card not because he needed more credit, but because he wanted to make use of its perks — in common with many people who pay off their balance.

Abbey Zero has been much publicised ahead of the summer holidays because it is one of the few cards not to charge foreign loading fees on purchases abroad. Phillips’s rejection means he cannot apply for another credit card from Abbey for six months.

Ed Mayo of Consumer Focus, the government’s consumer watchdog, said: “Credit card providers seem to have given their game away. By refusing credit to consumers with excellent scores, they appear to be measuring something other than risk.

“We need to know if the rules are being flouted and if people’s information is being used inappropriately. Consumers need reassurance and it’s up to the Financial Services Authority to look into this.”

Phillips has four other credit cards with a total limit of £50,000, but analysts said this was not unusual for someone a high six-figure salary. He doesn’t use the credit available and pays off each card in full.

Kevin Mountford, a former banker and now head of credit cards at Moneysupermarket said: “Banks are keen to improve their balance sheets by reducing the credit they make available to customers. They will do this based on the creditworthiness of the customer, but also how much profit they are able to make from them.”

“We have certainly seen a growing number of rejections of applicants who could only be described as being ‘too good’.”