After chopping the overnight cash rate by 50 basis points last week, the Reserve Bank of Australia (RBA) has trained its sight this time on credit card surcharges imposed by merchants.

Beginning Jan 1, 2013, merchants would be allowed to charge shoppers lower fees that actually cover the reasonable cost of card acceptance. With the RBA rule, stores, airlines, taxis and Web sites would be prohibited from charging excessive surcharges when paid by credit card.

The new policy was crafted after an RBA survey found that big merchants charge shoppers about two times when they swipe their credit cards. The report suggested the merchants were using surcharges to further generate revenue.

The study showed that credit card surcharges vary. Qantas imposes a $7.70 surcharge, Wotif, an online travel booking firms collects $5.50 and taxis that allow payment through Cabcharge slap passengers a 10 per cent surcharge of their fare.

Customers of Telstra are charged 1 per cent when they use their Visa, MasterCard and Amex, while it collects 2 per cent surcharge for Diners Club cardholders.

Qantas insisted that its surcharges do not recover more than the cost to the air carrier and stressed its surcharges are not unreasonable. However, Qantas promised to review the surcharges and respond later.

Visa and MasterCard welcomed the new RBA policy. However, Matt Levey, the spokesman of consumer group, Choice, pointed to some grey areas in the RBA rule, particularly what consists of reasonable cost of processing a credit card.

"At the end of the day it's actually going to come down to these agreements between the credit card providers and the merchants to actually draw down those costs," ABC quoted Mr Levey.