Credit card providers which opt to increase their rates are cashing in on their customers, it has been suggested.

Martyn Saville, senior researcher at Which?, believes levels of default cannot justify some of the high rates, which can be as much as 40 times the base rate.

"They are not making much money from current accounts and their other activities, so credit cards are an easy target for profit making," claimed Mr Saville.

He revealed that the average rate on a credit card is around 17 or 18 per cent, which the researcher said there is "no justification for … at all".

Figures from the Bank of England show the increase in total net lending to individuals in April (£1.3 billion) was higher than the March increase (£0.7 billion), but nevertheless below the previous six-month average.

The 12-month growth rate continued to fall by 0.3 percentage points to 1.8 per cent, while credit card lending increased by a net £0.3 billion.

The annual growth rate of consumer credit continued to fall, to 2.9 per cent, the Bank also revealed.