The Australian Competition and Consumer Commission (ACCC) will start tracking big supermarkets' compliance with a new ban on excessive pricing, effective July 1, the regulator said Friday.

The excessive pricing prohibition is applicable to large supermarket retailers with annual revenue of over AU$30 billion, a threshold that currently captures just Coles Group (ASX:COL) and Woolworths Group (ASX:WOW), the ACCC said.

Under the new rules, the regulator will consider various factors such as the cost of supplying a grocery product and what constitutes a reasonable margin for the supermarket to decide if pricing is appropriate.

The ACCC will initially focus its monitoring on a select group of products "where excessive pricing is likely to cause the most harm to consumers," said ACCC Acting Chair Catriona Lowe.