According to a report in today's Australian Financial Review, senior executives from National Foods told the ACCC that 74pc of white milk sold in supermarkets is under a brand owned by a chain store.

NatFoods owns the Pura milk brand, which also competes against the Coles and Woolworths labels that are often sold at a cheaper price.

In total housebrands now account for 57pc of all milk sold, with branded milk and milk sold at service stations and corner stores making up the remainder.

This is up from 25pc in 2000.

However, housebrands only account for 4-5pc of sales in the yoghurt market, the inquiry heard.

NatFoods group executive for grocery sales and marketing, Michael Harley, said that was because of the level of innovation in the yoghurt sector, whereas milk was considered a staple by consumers, the AFR reports.

Mr Harley said retail milk prices had risen in the last six months in line with farmgate prices and international demand.