Elective surgeries at western Sydney's Blacktown and Mount Druitt hospitals are set to be cut from 2020, according to the hospitals' head of surgery.

Elective surgeries at two western Sydney hospitals will be cut due to increasing pressure on resources and past overspending, according to the hospital's departmental head of surgery.

The revelation prompted NSW Labor on Wednesday to plead for the state government to stop the cuts.

In an email to staff on Sunday, Blacktown and Mount Druitt Hospital Head of Surgery Fred Betros said the two hospitals would be obliged from 2020 to reduce the number of elective surgeries performed.

The hospitals would perform eight fewer elective surgical procedures per week, Dr Betros said, with general surgery and orthopaedics likely hardest hit.

He blamed this reduction on resource constraints from the Western Sydney Local Health District, including an attempt to rectify past overspending.

"We do not support any reduction in elective surgical services at all. What was explained to us was that if we did not sort out how to do this as a department, it would be done for us by hospital administration," Dr Betros wrote.

"I have no doubt that if such changes are introduced, many patients will experience significant breaches in waiting times.

"I do not think any of us should be complicit with or approve of such a plan."

Dr Betros' letter was on Tuesday forwarded by a surgeon, Dr Richard Hanney, to NSW Health Minister Brad Hazzard and Labor counterpart Ryan Park.

Mr Park and Opposition Leader Jodi McKay on Wednesday accused the government of neglecting an economically disadvantaged community.

The entire Labor lower house caucus on Wednesday walked out of Question Time, dissatisfied with what they allege was Mr Hazzard's refusal to adequately address the matter.

"Elective surgery is essential surgery. It is needed by people, often our senior citizens, who are living in terrible pain," Ms McKay said.

In a statement on Wednesday, Western Sydney LHD chief executive Graeme Loy said all patients at Blacktown and Mount Druitt Hospitals over the past 12 months underwent elective surgery on time.

He said the NSW government was spending $700 million on the second stage of expanding the two hospitals.