The Premier and Planning Minister have repudiated Treasurer Andrew Constance's claim that 16,000 homes were expected to be built as part of the state government's redevelopment of a prime stretch of Sydney's inner harbour.

Mike Baird on Wednesday instead told an international summit convened to consider the future of the Bays Precinct that they were working with a "complete and utter blank canvas" for the 80-hectare sweep of public land between the Sydney Fish Market and White Bay.

"We're asking you, the best minds in the world with the best domestic minds, coming together to say what can be achieved in this space," Mr Baird said. "And I assure you that it is a complete and utter blank canvas."

The Premier's remarks were at odds with those made just a day earlier by the Treasurer at a curtain raiser for the two-day gathering of "celebrity city builders" looking at how best to undertake what will be the biggest urban renewal program since the Olympics.

"The Bays Precinct Urban Renewal is expected to create approximately 16,000 dwellings for the state," Mr Constance told a finance and investment summit on Tuesday.

Planning Minister Pru Goward also used her opening remarks to Wednesday's summit to disavow Mr Constance's figure.

"We are a city where almost everyone aspires to live close to our sparkling harbour, although I must say we've never set 16,000 people as a target," Ms Goward said.

It was the second time in recent months that the government has sought to distance itself from comments made by the Treasurer.

In October, Mr Constance told an industry breakfast that Sydney's 41 councils should be reduced to just five.

In that instance, Mr Baird was forced to clarify that Mr Constance had expressed a personal view that was not the government's, as the remarks sparked an angry response from the local government sector.

Sydney Lord Mayor Clover Moore said Mr Constance's latest remarks were "totally inappropriate".

"I don't believe long-term planning should be announced by the Treasurer at the beginning of the planning process," Cr Moore said. "This is really pulling the rug out from under the feet of all the fantastic people who are here."

UrbanGrowth director Matthew Quinn, who serves as chairman of the Bays Precinct Project Control Advisory Board, also sought to assure the summit the event was "not a sham or fait accompli with the outcomes already known".

This counted among the criticisms made by Leichhardt's mayor Rochelle Porteous and Greens MP Jamie Parker, who joined Labor in expressing their concern about Mr Constance's remarks.

Former Leichhardt mayor Darcy Byrne said 16,000 homes would be "more than currently exists in the neighbouring suburbs of Balmain, Rozelle and Annandale combined".

Mr Parker called on the Premier and Treasurer to reveal the source of the 16,000 figure. "It's clear they've done a capacity analysis, they've looked at the yield for the site, and that's where these numbers have come from," he said.

But a spokesman for Mr Constance said he would not be making any further comment and that "everything has been made clear" by the Premier and Planning Minister.

Urban planner and summit speaker Joe Berridge, who has worked on big urban regeneration projects in Britain, the US and Canada, said "no number at this stage of the game has a heck of a lot of reality".

"Nobody knows until you've done the work," he said. "Maybe you can get 25,000 units on there."

But "you've got to bring people along" and look at what could be done to immediately open up the site to greater community uses in the meantime, he said.

"The way you bring the community along is you say: 'This is what it looks like. This is another alternative. This is another alternative. These are the different implications. What do you think?'

"And I'm sure that is where this is going," Mr Berridge said.