Coles Myer chief executive Dennis Eck has rejected calls to break-up the group, claiming that Australia's largest retailer still had huge upside potential.

Coles Myer last week reported a 33% slide in net profit to A$196.4m (US$96.73m) for the first half and has been attempting to fix its struggling Myer Grace Bros and Target lines.

"I am very much still of the view that this company has a huge upside potential and it is our job to get that out, so people understand it," Mr Eck told Channel Nine's Business Sunday program.