LAS VEGAS >> A union for casino-hotel workers says it has reached a tentative agreement with MGM Resorts International, covering nearly half of the 50,000 employees threatening to strike in Las Vegas.

The deal between MGM and the Culinary Workers Union Local 226 was announced by the union in a tweet late Saturday. A tentative accord between the labor union and the other big casino employer threatened by the job action, Caesars Entertainment, was reached Friday afternoon.

“BREAKING. We are pleased to announce that a tentative agreement has been reached with MGMResortsIntl ,” read the late-night announcement on Twitter. “The historic new 5-year contract covers approximately 24,000 workers at 10 casino resorts on the Las Vegas Strip.”

Union spokeswoman Bethany Khan confirmed today that the tentative deal had been reached. MGM spokeswoman Mary Hynes deferred to the union for any further comment about the accord.

Some smaller casino operators have yet to reach agreements with the union and could still face the first citywide strike in more than 30 years.

The tentative deals with the two big operators came after thousands of bartenders, housekeepers, cocktail and food servers, porters, bellmen, cooks and other kitchen workers saw their contracts expire.

The union says the main sticking points have been wages, workplace training and job security as casino-hotels turn to technology that can displace workers. Employees want contract language that would protect them if properties are sold and an independent workload study for housekeepers.

Workers have voted to authorize a strike, but no date has been set. They have started signing up for strike pay, financial assistance and picketing shifts.

If there is a strike, visitors could witness workers picketing outside casino-hotels still in negotiations.

Companies have declined to provide details of their contingency plans, but hospitality experts say the properties will remain open, with replacement workers and managers carrying out additional tasks.

If the contract agreement sticks, a walkout would not affect Caesars’ Las Vegas Strip properties: Bally’s, Flamingo, Harrah’s, Paris, Planet Hollywood, The Cromwell, The Linq and Caesars Palace, including Nobu. The deal also would apply to the off-Strip Rio All-Suite Hotel and Casino.

The union has said Caesars workers had asked for a wage increase of 4.2 percent effective Friday, and annual increases of about 4 percent thereafter. The union previously said the company had offered an approximate 2.8 percent increase for each of the five years.

A permanent deal by the union with MGM will ensure that a walkout does not affect its properties: Aria Resort & Casino, Bellagio Hotel & Casino, Circus Circus Hotel & Resort, Excalibur Hotel & Casino, Luxor Hotel & Casino, MGM Grand Las Vegas, The Mirage, New York-New York Hotel & Casino, Mandalay Bay, including the Delano and Monte Carlo Hotel & Casino, now known as Park MGM.

In MGM’s case, the union has asked for average annual wage increases of 4 percent for each of the next five years. It says the company has countered with an approximate 2.7 percent raise.

The average worker on the Las Vegas Strip makes about $23 an hour, including benefits such as premium-free health care, a pension and a 401(k) retirement savings plan.

The last citywide strike was in 1984, costing the city and workers millions of dollars.