The Fair Trade Commission will look into recent decisions by major commercial banks to impose fees for Saturday transactions at automated teller machines.
FTC Secretary General Akio Yamada said Wednesday that the moves do not contravene the antimonopoly law if they are based on "each bank's judgment, but it is a problem if they stem from talks" among banks.
It had been free to use an ATM until early in the afternoon on Saturdays, but UFJ Bank began charging fees late last year, while the Bank of Tokyo-Mitsubishi will follow suit this Saturday. Sumitomo Mitsui Banking Corp. will introduce the fees in March.
Mizuho Bank is studying a plan to begin charging Saturday fees by this fall.
It is "extremely important" for banks to abandon their "me too" business stance, Yamada said.
During a Diet session Feb. 6, Prime Minister Junichiro Koizumi described the banks' recent moves as "odd."