LAS VEGAS >> A union for casino workers and one of the largest resort operators in Las Vegas reached a tentative labor agreement Friday that would cover about a quarter of the 50,000 employees threatening the first citywide strike in more than 30 years.

The new five-year deal with Caesars Entertainment covers about 12,000 bartenders, housekeepers, kitchen workers and others at nine casino-resorts on the Las Vegas Strip, the Culinary Workers Union Local 226 said. It declined to provide details because workers have not approved the contract, but generally both sides agreed to wage increases and stronger language against sexual harassment.

“We feel very good about the contract,” said Geoconda Arguello-Kline, union secretary-treasurer. “We feel like the company got what they need for their business to continue, and we feel like we can still provide the American dream for the members.”

It comes just after tens of thousands of bartenders, housekeepers, cocktail and food servers, porters, bellmen, cooks and other kitchen workers saw their contracts expire. The union has yet to reach new agreements with MGM Resorts International and other smaller casino-hotel operators on the Strip and in downtown Las Vegas.

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

“Technology is being heavily introduced in the casino industry, and unfortunately, they are not … investing in us,” said Kimberly Ireland, bell desk dispatcher at The Mirage. “MGM Resorts International has not agreed to any of our terms pertaining to job security, safety, our housekeeping study, so we are prepared to do whatever it takes to make sure that we secure our future.”

MGM said Friday that it has “made good progress in resolving the remaining issues.” Caesars did not respond to a request for comment.

“We remain dedicated to negotiating a contract that demonstrates our commitment to employees and their families while our company continues creating good jobs and future opportunities in Las Vegas,” MGM said in a statement.

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.

Dozens of workers gathered Friday to put together bilingual picket signs reading “Las Vegas hotel and restaurant workers, MGM Resorts, on strike.” The walls of what they christened as their strike headquarters had maps of properties operated by MGM with the entrances clearly marked.

If there is a strike, visitors could see workers picketing outside casino-hotels still in negotiations, including Aria, Bellagio and Mandalay Bay.

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.

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.