An independent grocer has accused Coles and Woolworths of killing off competition and building oversized and unprofitable stores in marginal sites like Ulladulla.

The new multi-million dollar Woolworths complex on the Princes Highway at Ulladulla opened last month (May) and includes a supermarket, Macs Liquor and 10 specialty shops.

Joss De Bruin who represents smaller grocers like IGA and Foodworks has told the ABC that supermarkets like the Ulladulla Woolies are inappropriately sized and built just to lock out competition.

Mr De Bruin is calling for competition and planning laws to be changed so allowable retail supermarket floor space is determined by the size of the population.

Statistics show that Coles and Woolies control around 80% of dry groceries and nearly 60% of fresh produce.