German discount retailer Aldi is undercutting prices at other Australian supermarkets by an average of 19%, according to a research report conducted by Macquarie Equities.

Since Aldi's much debated arrival into the A$42bn Australian retail sector last week, the second largest grocer in the country, Coles Myer, is seen to be suffering most from the competition. Woolworths appears to faring a little better, its prices are 7% higher than its German rival, according to the report.

At struggling supermarket chain Franklins, currently the third largest in the sector, prices were about 8% higher than at Aldi.