(Reuters) - Hundreds of nurses and midwives across Ramsay Health Care's 17 hospitals in Australia's New South Wales will go on a 24-hour strike on Tuesday, demanding a pay hike and better staffing, a union representing them said on Monday.

"Our members are demanding a 20% pay increase over three years and mandated nurse/midwife to patient ratios across all wards and units in Ramsay hospitals," New South Wales Nurses and Midwives' Association (NSWNMA) General Secretary Shaye Candish said in a statement. The association also plans to protest outside Ramsay's annual general meeting venue on Tuesday.

Ramsay nurses and midwives in Queensland are paid up to 14% more than those in NSW, according to the union.

A majority of the staff had already voted down two pay offers by Ramsay, one of Australia's largest private hospital operators, since they started pay negotiations in April 2023, and are yet to reach an agreement with the hospital operator, the union further said.

"We're urging Ramsay to come to the table and resolve this long-running pay dispute before Christmas," Candish said.

Ramsay did not immediately respond to Reuters' request for comment.

Shares of Ramsay slipped 0.5% to A$38.84, while the broader ASX index notched a record high earlier in the day.

(Reporting by Rajasik Mukherjee in Bengaluru; Editing by Sumana Nandy)