The Warehouse Group has laid a complaint against Sanitarium over its decision to stop supplying Weet-Bix - the breakfast of champions - from the end of the month and the Commerce Commission is "extremely concerned".
The Warehouse says it's unfair that the cereal will be sold to the two major grocery chains, but not in their stores.
Warehouse Group CEO Nick Grayston says Weet-Bix producer Sanitarium is citing supply issues, but he doesn't think that's good enough.
Commerce Commission chair of the board John Small spoke to Ingrid Hipkiss.