Mr Ayres and Premier Gladys Berejiklian announced the spending package on Friday, which will include new rectangular stadiums at Moore Park and Olympic Park to be built over the next five years, but declined to release any economic analysis or business case to support the decision.

"My expectation is that with better quality facilities more people will come and attend matches," said Mr Ayres.

The spending package reverses a decision made last year by former premier Mike Baird not to build a new stadium at Moore Park to replace the 30-year-old Allianz Stadium.

But it also pushes out the total expected cost of the government's stadium spending to beyond $2.5 billion, with potentially hundreds of millions yet to come.

A new stadium at Moore Park, to be built between 2018 and 2021 on the existing site of Allianz Stadium, is expected to cost around $705 million. A new 75,000-seat stadium at Olympic Park to replace ANZ Stadium is planned to be built between 2019 and 2022 at a cost of $1.25 billion.

In addition, the government is spending $300 million on a new Parramatta Stadium to open in 2019, and has spent around $200 million buying ANZ Stadium from its former private owners.

The government has also said it intends to build another indoor sporting arena near central Sydney, though Mr Ayres said a business case was still being developed.

Fairfax Media has previously reported that Infrastructure NSW analysis said there would be no economic benefit from building a new stadium at Moore Park to replace Allianz, and a report on Friday said state cabinet was told the projects would not have a positive economic benefit.

Ms Berejiklian did not release any analysis to support the spending spree on Friday, but said she had "based her decision on facts".

"Rest assured, I am not someone who would spend a dollar of taxpayers' money unless I thought it was worth it," Ms Berejiklian said. "I'm not someone who takes a decision rashly.

"For every dollar that we spend, we will also ensure we get the best price for our taxpayer."

Ms Berejiklian and Mr Ayres were flanked by the chief executive of the NRL, Todd Greenberg, the chief executive of Football Federation Australia, David Gallop, the chief executive of the Australian Rugby Union, Bill Pulver, the chairman of the Sydney Cricket & Sports Ground Trust, Tony Shepherd, and the chairman of Venues NSW, Christine McLoughlin, for the announcement in the Domain on Friday.

Mr Shepherd said that the SCG Trust, which has been pushing for a new stadium at Moore Park, would have had to close Allianz down in 2019.

"The safety reports we've got were quite alarming and the minister wasn't joking when he said if we can't get something done??? by 2019 we will have to close it down," Mr Shepherd said.

"We managed it within our capability with the money we had and you can throw a lot of money at something forever but in the end we had to recognise the reality that this stadium has passed its useful life."

Last year, the three tenants at Allianz Stadium - Sydney FC, the Roosters and the Waratahs - released a statement saying that building a new stadium at Moore Park and requiring them to relocate would cause them major damage.

"When teams are displaced from their established home ground, the impact is negative and of a long-term nature," the three clubs said in a statement last April. "Some clubs never recover."

Mr Ayres did not rule out compensating these clubs to allay their concerns while a new Moore Park stadium was built.

"We are going to work with every single one of the tenants across all of the assets that are owned by the NSW government," Mr Ayres said.

The government said it had secured an agreement with the NRL to play the next 25 grand finals in Sydney. The 2020 grand final will be played at the SCG, grand finals in 2021 and 2022 will be played at a new Sydney Football Stadium at Moore Park, and the grand final will revert to Olympic Park from 2023.

At Berala Public School on Friday, Labor leader Luke Foley said: "there's 100,000 schoolchildren learning in demountable classrooms [in NSW] and that's why I will not support $2.5 billion in public money going to sporting stadiums."

"What the Premier's announced today is a total capitulation to unelected powerbrokers on the SCG Trust," Mr Foley said.