CONSUMERS could lose as much as £5,000 by staying loyal to their banks rather than switching to the best deals.

Halifax customers will be the hardest hit, according to the report from data firm Moneyfacts, which looked at the cost of sticking with your bank for all your financial needs.

The survey came as banks were revealed to be making an extra £500m in profits from their British customers despite the credit crunch. They have raised profits from their UK divisions by 12 per cent to £4.3 billion since the first half of last year.

The research looked at the cost of a mortgage, loan and credit card from the big six high-street banks, compared with the best buys on the market. It also looked at how much extra interest you could earn on your savings and current account by switching to the best deals.

If you took out a two-year fixed-rate mortgage of £150,000 with Halifax, a five-year loan of £7,500 and had £3,000 of debts on your credit card debt for one year, you would pay a total of £31,249 in interest over the life of the deals.

That compares with just £26,545 if you took the best-buy product in each category – a saving of £4,704.

If you also had £5,000 in a Halifax instant-access savings account and £1,000 in a savings account, you would lose out on £321 in interest compared with the best buys – meaning you will lose out on £5,024 by sticking with Halifax.

Michelle Slade, analyst at Moneyfacts, said: “Consumers who are loyal to Halifax are the hardest hit, with Royal Bank of Scotland customers not far behind at nearly £3,500. HSBC customers come out best by being just under £2,000 worse off, but that is still a large amount, particularly in the current economic climate where every penny counts.

“The big banks trade on their names and it is disappointing that they do not offer more competitive deals to their customers. The banks are not loyal to you, so why should you be loyal to them?”

A separate survey from Moneyexpert.com, a financial website, has also found that credit card firms are turning the screw on customers, making it doubly important to shop around for the best deal.

The average credit card interest rate has hit 17.4 per cent compared with 16.8 per cent in February despite two Bank of England rate cuts - from 5.5 per cent to 5 per cent - over the same period.

More than 72 cards now charge standard rates of 17.9 per cent or higher compared with just 59 in February. There are even cards charging more than 40 per cent such as BA Amex Premium Plus at 43.5 per cent and Ultima from Citibank at 41.2 per cent.

Sean Gardner, director of MoneyExpert, said: “Homeowners have been the most visible losers in the credit crunch but credit card customers are also sharing the pain.There is however still plenty of choice in the credit card market and a lot of competition. Customers paying higher rates on debts should review their credit card as a matter of urgency and switch.”