Progress was also reliant on shoring up funding for staffing, which was not part of the $63 million promise, NSW Ambulance Commissioner Dominic Morgan told a budget estimates hearing on Monday.

"When do we expect that the first regional base will be operational in (the next four years)?" Nationals MP Wes Fang asked the ambulance chief.

"It will depend on future funding being provided to operate those bases," Dr Morgan replied.

It usually took two years from commitment to lift-off for a new helicopter but government could choose "other options" to be faster, Dr Morgan said.

Health secretary Susan Pearce said it was a complex issue.

"Helicopter bases are, to be perfectly honest, quite contentious in respect to their location," Ms Pearce said.

"We need to do some very careful planning because we've had issues in the past where we've had bases that subsequently have been required to move."

The Nationals demanded Labor come clean on how it planned to deliver the promised services.

"The longer Labor delays its commitment, the longer our communities will have to wait for much needed resources that could reduce emergency response times," opposition regional health spokesman Gurmesh Singh told AAP.

"Chris Minns has already broken his promise to deliver 500 regional intensive and extended care paramedics, and this is just another case of saying one thing to win votes and then not following through."

Health Minister Ryan Park declined to say which four locations were under consideration, instead touting the deployment of 500 regional paramedics, new-age rescue ambulances and several incentives to boost the medical workforce.

“It's been a productive first 21 months of the Minns Labor government, making significant investments into regional and rural health," Mr Park said.

“We look forward to sharing more about the delivery of mSore ambulance helicopter bases in due course."

License this article