Unionized nurses have started strike action across Australia's New South Wales (NSW) as part of their campaign for extra staff in hospitals, local media reported Wednesday.

NSW Nurses and Midwives Association (NSWNMA) members from more than 180 public hospitals are taking part in the industrial action on Wednesday, with some nurses walking off the job for as long as 24 hours, according to the Australian Associated Press (AAP).

The strike will leave many hospitals with minimum nursing staff.

The NSWNMA said hospitals need extra nursing staff to ensure adequate patient care as safer patient care is more important than budgets.

NSW Health Minister Jillian Skinner said the government had increased its nursing and midwifery workforce.

"I'm proud we have met and exceeded our promise to increase frontline nursing staff across NSW, with more than 4000 extra nurses and midwives recruited since the election," Skinner said in a statement.