The immediate past NSW government architect has slammed proposed changes to Barangaroo for James Packer's $1.5 billion casino resort, declaring there is a lack of balance between private gain and public benefit.

Peter Mould, who held the position between 2006 and 2012, says the proposed modification to Barangaroo South is so significant it warrants "serious rethinking of the concept plan".

A view of Barangaroo. Credit:Daniel Munoz

"I've always held that the public realm is as important as the private realm," he told Fairfax Media.

"We certainly need development, we certainly want people to make a profit. There's no problem with that.