Using a credit card has become a more expensive way to spend

Its latest survey shows that six card companies have made big changes to their charges in the past two weeks.

Offers to transfer a card balance free of charge have almost all disappeared.

Moneyfacts says banks are responding to last year's ruling by the Office of Fair Trading (OFT) that credit card default fees should be cut to just �12.

"Battling with rising bad debts and a huge loss in revenue from the capping of default fees, credit card providers have been forced to look for other ways to maintain their income stream," said Michelle Slade of Moneyfacts.

"Changes range from interest rate increases, by as much as 10% (on cash transactions), to shortening of interest-free deals," she added.

Balance transfers

The six major credit card firms highlighted by Moneyfacts for the recent introduction of higher charges are the Co-operative Bank, GE Money, Marks & Spencer, the Nationwide and Northern Rock.

Perhaps the sneakiest of all is the requirement to make purchases as part of a 0% balance transfer deal Moneyfacts

But Moneyfacts accuses Lloyds TSB of being particularly sneaky.

"Cash withdrawal fees and foreign usage charges are rising, but perhaps the sneakiest of all is the requirement to make purchases as part of a 0% balance transfer deal," said Michelle Slade.

Moneyfacts says Lloyds TSB is negating the apparent advantage of its 0% nine-month deal for balance transfers, by insisting that customers make a purchase of at least �100 with their new card within the first three months.

That purchase will attract an interest charge of either 15.9% or 17.9% and will not be paid off at all until the cheaper, transferred, debt has been paid off in full.

However, in response, Lloyds TSB said that the full terms of the 0% deal was "very clearly communicated in customer literature."

In addition, the bank said that the �100 purchase that customers had to make to obtain the 0% deal was itself subject to an initial three-month interest free period.

OFT

All this has been part of a growing trend.

In the aftermath of the OFT's ruling that credit card default fees should be slashed to just �12, many credit card companies raised their basic interest rates.

Since then, the banking group HBOS has revealed that it would lose �60m in income this coming year as a result of the OFT's ruling.

Other charges were introduced as well.

Last month, Lloyds TSB announced it would charge customers �35 a year if they did not use their credit cards enough.

And in January, HSBC said it would charge much higher interest rates when customers used their credit cards for gambling.

Meanwhile, 0% deals for balance transfers, which gave birth to a breed of people called "rate tarts", now almost all come with a transfer fee attached, typically of 3%.