The $700 million redevelopment of ANZ Stadium is in limbo after the business case for the project showed it will actually cost $1.6 billion.

As part of the NSW Government's stadia policy, ANZ Stadium at Olympic Park is to be refurbished into a world class rectangular stadium to seat 70,000.

The business case, to be handed to the Sports Minister in August, revealed it will cost more than double what the government originally estimated.

Sources have told 9NEWS spending $1.6 billion on ANZ Stadium would not be acceptable to the community, putting the project in its current form at significant risk.

Former Premier Mike Baird announced their entire budget for the "stadia strategy" was $1.6 billion in April 2016.

9NEWS understands the cost of redeveloping ANZ Stadium is now more than double what the government originally thought. (AAP)

ANZ Stadium received a $700 million refurbishment, Parramatta Stadium is being rebuilt for $340 million and there was $500 million for Allianz Stadium and the SCG at Moore Park.

It followed a bitter brawl, nicknamed 'stadium wars', between interest groups at Olympic Park and Moore Park, who were lobbying for the biggest slice of the pie.

9NEWS understands the business case for the ANZ redevelopment will have more than one option, but none of them are close to the original cost.

The upgrades are to be partly funded by the privatisation of the Land Titles Office but 9NEWS understands Treasurer Dominic Perrottet won't hand over a cent more from that sale than already promised.

"The stadium in the geographic heart of Sydney needs what was promised, a world class refurbishment," Opposition Leader Luke Foley said.

The Government has owned ANZ Stadium since June 2016, spending $220 million to buy out the final 15 years of the lease in preparation for the project.

Premier Gladys Berejiklian recommitted to the ANZ Stadium redevelopment in April.