Labor says it will consider a royal commission-like inquiry into the NSW government's $2.5 billion splurge on sporting stadiums if elected in 2019.

Opposition Leader Luke Foley on Tuesday declared he was putting Premier Gladys Berejiklian “on notice” over plans to knock down and rebuild stadiums at Sydney’s Olympic Park and Moore Park.

It follows a leaked cost-benefit analysis by consultants KPMG that suggests demolishing and rebuilding Allianz Stadium would merely “break-even”.

While a simple refurbishment would deliver “significantly negative net economic outcomes”, the economic return on a rebuild would be no greater than the investment, according to the analysis obtained by News Corp Australia.

Mr Foley said the proposal was untenable and questioned the government’s haste to commit to the projects ahead of the state election in March 2019.

“If you want to rush indecently here and bypass public scrutiny, parliamentary scrutiny, the proper planning system, proper due process, then an incoming Labor government will reserve the right to establish a special commission of inquiry with royal commission powers into this stadium scandal,” he said.

“I’ve just put the government on notice.”

Sports Minister Stuart Ayres in a statement said: “The NSW government is awaiting the final business case for Allianz Stadium and Infrastructure NSW is developing a strategic business case for ANZ Stadium.”

Meanwhile, Liberal MP Matthew Mason-Cox criticised the government for prioritising “a couple of sporting stadiums before the welfare of the most vulnerable children and families in our community”.

The former Baird-government minister said the party room hadn’t yet been told where the business case stood but “all the evidence points to it being difficult to justify”.

“The party room hasn’t had time to reflect on this, we haven’t seen a business case, and I think the government needs to be more transparent in its decision-making,” he told Fairfax Media on Tuesday.