We'll help with airport: NSW premier

NSW Premier Gladys Berejiklian says people aren't worried about who will build or operate Sydney's second airport, so long as it's done as quickly as possible.

NSW Premier Gladys Berejiklian (AAP) Source: AAP

The NSW government will support the federal government to ensure a second Sydney airport is built in the city's west as quickly as possible, despite Sydney Airport turning down the opportunity to develop the project.

Premier Gladys Berejiklian says Sydney Airport's decision, announced on Tuesday morning, leaves the federal government with "some really exciting options" and the state government will continue to invest in the project.

"We are a stakeholder, it's in our state, we have a huge interest in making sure it happens and we will support in whichever way we can the federal government to make it happen as quickly as possible," she told reporters in Sydney on Tuesday.

"I think the community wants to see the project come to life as opposed to necessarily worrying about who builds or who operates it."

Sydney Airport's refusal had been widely expected after the federal government in December ruled out any direct financial support towards the cost of building and operating the proposed $5 billion project at Badgerys Creek.