Thousands of nurses at three major hospitals in New York City began to strike on Monday, amid a severe flu season and broader pressures on the US healthcare system.

The walkout impacts roughly 15,000 nurses at hospitals including Mount Sinai Medical Centre and NewYork-Presbyterian in Manhattan as well as Montefiore Medical Centre in the Bronx. New York City Mayor Zohran Mamdani joined striking nurses on the picket line in Washington Heights.

“All parties must return immediately to the negotiating table,” Mamdani said in brief remarks. “They must bargain in good faith.”

A labour dispute is at the centre of the conflict, with workers represented by the New York State Nurses Association arguing that hospital management is threatening to cull benefits, the union said in a statement.

Hospital management at all three systems said the decision to walk out is “reckless”, in a statement before the strike.

Nurses from New York-Presbyterian/Columbia University Irving Medical Centre strike outside the hospital on Monday. Photo: Getty Images via AFPNurses from New York-Presbyterian/Columbia University Irving Medical Centre strike outside the hospital on Monday. Photo: Getty Images via AFP

On Monday, Mount Sinai Health System said it has readied 1,400 qualified and specialised nurses and is “prepared to continue to provide safe patient care for as long as this strike lasts”.