NSW Labor Leader Chris Minns says investment in overseas manufactured ferries, trains and trams has led to delays and unforeseen repairs, cancelling out any savings made by purchasing stock offshore.

"We're getting infrastructure that is cracked, or defective, or isn't working," Mr Minns told reporters on Monday.

He cited recent steering issues that forced three Chinese-built Manly ferries out of service, the fleet of defect-riddled Parramatta River ferries, built in Indonesia, and Spanish-built light rail trams, taken off the tracks after cracking was found in the carriages.

"The government seems committed to building things offshore and refuses to believe what's possible right here in NSW," he said.

It comes after Mr Minns launched the party's new policy to replace ageing rail stock with a locally-built fleet at the NSW Labor conference on Sunday.

Treasurer Matt Kean says he wants to secure the best deal for taxpayers when it comes to new ferries and trains, but stopped short of committing to building infrastructure within the state.

"We should be getting the best services, the best infrastructure for the people of NSW," Mr Kean told reporters.

"We want to make sure that taxpayer dollars are spent wisely and we get the best bang for our buck."

NSW Transport bureaucrats came close to buying an additional seven defect-riddled Parramatta River ferries, before an intervention by Transport Minister David Elliott, The Daily Telegraph reported on Monday.

The Indonesian-designed ferries have more than 40 defects, including being unsafe for passengers to travel on at night, and being too high to have passengers seated on the top deck as they pass under two bridges on the Parramatta River.

Australian Associated Press