The $2 billion cost to rebuild two Sydney stadiums is close to half the price tag for the city's 2000 Olympic Games venues.
According to a 2002 report to the NSW government, the state's contribution to the games construction project was $3 billion - or an estimated $4.6 billion at today's prices.
This included building an Olympic Stadium, Aquatic Centre, Athletes Village, Homebush Bay rail line as and 11 other games venues.
NSW Opposition leader Luke Foley on Tuesday labelled the new spending proposed by the coalition government a "monumental waste of taxpayer dollars".
"The revelation the $2 billion cost is almost half of what was spent on all of the 2000 Olympics infrastructure show it's a terrible deal for the NSW taxpayer," Greens sports spokesman Justin Field said in a statement.
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The government's plan, announced last month, includes a new 45,000 seat arena to replace Allianz stadium at Moore Park by 2021.
A 75,000 capacity stadium would also be built by 2022 after the 17-year-old Sydney Olympic Park facility is knocked down.
By Tuesday morning, More than 111,000 people had signed a change.org petition calling on the government to back away from the projects.
