LONDON (Reuters) - There is no effective competition in core credit card services where Visa and Mastercard ( MA ) are the biggest players, and more transparency for users is needed, Britain's Payment Systems Regulator said in an interim report on Tuesday.

"The PSR found that over the past five years, and after taking account of volume changes, Mastercard ( MA ) and Visa have increased their scheme and processing fees by more than 30% in real terms. There is little evidence that the quality of service has improved at the same rate," the PSR said in a statement.

The PSR said it has proposed "remedies" for public consultation, that include improved transparency for users, and obligations on Mastercard ( MA ) and Visa to explain, consult on and/or document the reasons for price changes.

It said it has also proposed greater reporting of financial information to the PSR on an on-going basis to improve scrutiny of Mastercard ( MA ) and Visa's UK operations going forward.