Premier Gladys Berejiklian on Sunday announced the government would put $450 million towards stage two of the Nepean Hospital redevelopment, on top of $576 million for the first stage which is under construction.

"Planning has to start now for stage two and not only are we doing that work but we're also committing the dollars," Ms Berejiklian told reporters at the hospital.

The announcement came on the same day the state opposition launched a campaign to fund schools and hospitals before stadiums, with Labor critical of the government's multi-billion dollar plan to knock down and rebuild two stadiums in addition to upgrading another.

At the launch, held one year out from the next state election, opposition leader Luke Foley announced a Labor government would allocate $300 million from the "reckless stadium splurge" to air condition hundreds of schools across the state.

He also committed a $50 million increase in funding to all suburban and regional public libraries, saying in a media release that the money would help upgrade facilities and purchase equipment.

"The Berejiklian Government has the wrong priorities. Labor prefers to invest in schools, hospitals and libraries," Mr Foley said.

But Ms Berejiklian told reporters at Nepean Hospital the government was putting money where it was needed and had so far committed almost $5 billion to western Sydney's health infrastructure.

"A lot of hot air can be talked about but action is what matters to people and action is what really makes a difference to people's lives," she said.

Australian Associated Press