Supermarket giants that introduced a milk levy to support drought-affected farmers have been slammed for the "half-baked" plan by federal Agriculture Minister David Littleproud.
The minister said both Coles and Woolworths failed to follow through with the original idea of a 10-cent-a-litre levy on all milk brands that would be paid to processors that supply supermarkets.
However he took particular aim at Coles and said the supermarket was forced to take part in the scheme when rival Woolworth's signed up.
"The result is a half-baked policy which only applies to Coles' 3-litre variety of their own milk brand - and may not even go back to the farmers who supply that tiny portion of drinking milk," he said in a statement on Sunday.
But Coles hit back.
"It is disappointing that the Minister has chosen to criticise Coles - which has already committed over $12m for drought relief - before becoming familiar with the facts," a spokesman said.
"Coles established the Dairy Drought Relief Fund to ensure 100 per cent of the funds raised from this 30c increase on the price of Coles own brand 3L milk will be donated directly to dairy farmers affected by drought."
The company appointed PwC as an independent auditor to oversee the application administration process and verify funds have been allocated to the farmers as promised, the spokesman said.
The agriculture minister also took Woolworths and Aldi to task.
Woolworths has only applying the levy to their own $1 milk and Aldi has refused to look at a levy at all, he said.
"The big German can go and take a running jump if they can't be bothered to support Australian dairy farmers," Mr Littleproud said.
"The best thing shoppers can do is buy branded milk, not supermarket brand milk or better still, shop at independent grocers.
In September, dairy farmers called for a 10-cent-a-litre levy on all milk sales to help farmers battling drought.
Coles and Woolworths initially announced a temporary levy on their three-litre generic milk, raising the price from $3 to $3.30, with the extra money given to drought-stricken producers.
Woolworths' levy was to apply until mid-October, when it introduced a special drought relief range of milk at $1.10 per litre in Queensland, NSW, ACT and Victoria, with funds going to farmers in those states.
Coles will increase the price of its 3-litre branded milk until the end of the year.
Woolworths and Aldi have yet to respond to the comments.