Prime Minister Malcolm Turnbull has confirmed the federal government will back a fast train linking Sydney’s second airport at Badgerys Creek to the city.
It comes as leaders meet at a Western Sydney Ideas Summit, with keynote addresses from NSW Premier Mike Baird, Opposition Leader Luke Foley and head of the Greater Sydney Commission Lucy Turnbull.
The Western Sydney Airport will be "rail ready" by the time it opens, Mr Turnbull told ABC radio.
"What we are doing is working with the state government to see how we can bring the rail to the airport and more rail to western Sydney much sooner," he said.
"Ideally when the airport opens."
The federal government has already committed $2.9 billion in new roads spending to support the construction of a new airport, along with $700 million from the state government for a western Sydney road network.
But Mr Turnbull did not reveal a dollar figure for any rail projects.
Sydney's second airport is set to be completed by 2026, but traffic forecasts show there won't be a demand for a rail link until the 2040s, Mr Turnbull said.
Mr Baird said the rail link was a "critical piece of infrastructure required over the long term".
"If the prime minister is looking at making that investment, we welcome it," he told the Nine Network.