Las Vegas hotels and casinos face a strike by 50,000 workers from June 1 without a last-minute deal to settle a dispute with the Culinary Workers Union of Nevada.

The strike threatens properties including Caesars Palace, Planet Hollywood, Bellagio, the MGM Grand, Mandalay Bay and Stratosphere.

The Culinary Workers Union represents bar staff, waiters, cooks, housekeepers, porters and other workers at 34 casino resorts on the Las Vegas Strip and in Downtown Las Vegas.

It is seeking new five-year contracts with the resorts and held a strike ballot this week as the May 31 deadline for expiry of the current contracts approaches.

Union negotiators are demanding increased wages, guarantees on jobs and health care, and tougher action against sexual harassment of staff.

They warn a strike would involve about half the hospitality workforce in the city.

Chad Neanover, a cook at Margaritaville, said he wants to prevent his job being outsourced “to a robot” as rapid automation is forecast to cut a swathe of hospitality jobs in the next five years.

Neanover said: “We know technology is coming, but workers shouldn’t be pushed out or left behind.

“Casino companies should ensure technology is harnessed to improve quality and safety in the workplace, not as a way to eliminate our jobs.”

Union secretary Geoconda Argüello-Kline said: “We want to come to an agreement, but the union and workers are preparing for a citywide strike if contracts are not settled by June 1.”

The last strike by Culinary Union members, in 1984, lasted 67 days.