The Reserve Bank will consider intervening in rules that stop retailers from surcharging customers who use buy now, pay later schemes, sparking fresh warnings about the risks to Afterpay's business model and sending its shares tumbling.

As the buy now, pay later (BNPL) sector grows in popularity, the central bank has given its most explicit signal yet that it could take "policy action" over the cost to merchants of accepting such payments.

Stopping retailers from passing on the cost of Afterpay to customers is a key part of its business model, some analysts said. Credit:Dominic Lorrimer

In the annual report of its Payments System Board, the RBA this week said a review next year would look at "no surcharge" rules imposed by BNPL operators.

These prevent retailers from charging customers a surcharge for paying in this way, in contrast to credit cards, where retailers are allowed to add a surcharge to cover their extra payment costs.