LONDON, May 21 (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.