Mr Keating,the former prime minister and a former chair of the Barangaroo Design Excellence Review Panel,said he understood the government wanted to ameliorate some of the cost of the railway station.

"But I think the cost of the railway should be attributed to the whole area of Millers Point and not just this building,"Mr Keating said."In other words,the station is an element of common infrastructure."

He said the proposed floor space limit of 120,000 square metres was already quite ambitious."Taking this further to 150,000 square metres could be squeezing the lemon too hard,"Mr Keating said.

However,Mr Keating said"there is a distinct possibility of coming up with a good architectural solution,particularly now the railway is going ahead".

"I think it's possible to do something architecturally really good and I think this is what the government is seeking to do,"he said,adding the government"certainly understands"the importance of the site.

"This is where the built structure meets the headland park,and this built structure will sit alongside the open green space of Barangaroo Central,"Mr Keating said."So the building has to be sensitive to its location."

The lord mayor,Clover Moore,has been highly critical of the development process at Barangaroo. She said"accommodating the new train station should not be used to justify yet another increase to floor space or towers at Barangaroo Central".

"There is more than enough density to ensure the station is well patronised and in fact it is essential to avoid gridlock in Barangaroo."

The area will not include any affordable or key worker housing component,and Mr van der Laan said the government would not prescribe the mix of residential and commercial buildings.

"It is the place that people will want to come to to live,work and play,"he said."It will be vibrant,it will be dynamic,there will be plenty of things to do there at every hour of the day."