Walmart workers are threatening to strike on the busiest shopping day of the year – Black Friday.

The walkout, scheduled for next month on the day after Thanksgiving, is set to cause chaos across Dallas, San Diego, Chicago and Los Angeles.

Today, a meeting at Walmart’s headquarters in Bentonville, Arkansas was interrupted by 200 protesters waving placards and chanting.

Walmart is the world’s largest private employer and has long been a target of workers’ rights groups, who advocate higher wages, more flexibility in hours and an end to punishments, such as reduced shifts, which they claim are meted out to staff seeking to unionize.

Evelin Cruz, a department manager, told ABC News that for many years she kept quiet about what she views as the company’s unjust practices because she was afraid of being fired if she spoke out.

Evelin Cruz, who works at the Pico Rivera Walmart in California, is one of thousands of members of Our Walmart, an organization backed by the United Food and Commercial Workers (UFCW).

Leaders of Our Walmart, the National Consumers League and other groups today said they will join Walmart workers outside stores on Black Friday if their demands are not met.

Walmart workers are threatening to strike on Black Friday, the busiest shopping day of the year

National Organization of Women president Terry O’Neill said her group would join in the action on Black Friday, to show “solidarity with the workers who are walking off the job”.

Last Thursday, about 30 employees from the Pico Rivera Walmart demonstrated outside the store with signs that read “Stand Up, Live Better, Stop Retaliation” and “Stop Trying to Silence Us”.

The protest over working conditions was coordinated with actions at eight other Walmart stores across California protesting against working conditions and treatment.

It was the first-ever walkout in the company’s 50-year history, said Dawn Le, a spokeswoman for Making Change at Walmart, a coalition whose mission is to change the way the firm conducts business.

“Everyone else has a union,” said Dawn Le.

“Workers in every other country – Japan, the U.K., Nicaragua, South Africa, Brazil, Argentina – have been able to form a union, except the U.S. and Canada.

“We just don’t understand the double standard Walmart has. How come those in other countries get to have a voice, yet not in the U.S., its home country?”

Walmart spokesman Dan Fogleman disputed her claims, insisting that most employees have “repeatedly rejected unionization”.

“They seem to recognize that Walmart has some of the best jobs in the retail industry – good pay, affordable benefits and the chance for advancement,” he said.

Walmart has hit the headlines on several recent occasions. In mid-September, warehouse workers in Southern California went on a 15-day strike that included a six-day, 50-mile pilgrimage for safe jobs.

Around the same time, hundreds of people marched in Dallas and San Diego, demanding better work conditions.

On Monday, Chicago riot police arrested 17 peaceful protesters blocking the entrance to a warehouse that supplies Walmart stores in support of striking workers.

The company is also now facing another sex discrimination lawsuit, filed on behalf of 100,000 women in California and Tennessee.

Dan Schlademan, director of Making Change at Walmart, said: “Workers find how Walmart has tried to retaliate by cutting their hours and not scheduling them for certain shifts when they tried to speak out, and they’re tired of it.”

The $16 billion company, however, argues that the California rally was simply a “publicity stunt by the UFCW to seek media attention in order to further their political agenda and financial objectives”, according to Dan Schlademan.

Evelin Cruz, who started on $7.40 an hour and now makes $13.20, said: “We just wanted to be treated like humans, not robots. We do have health insurance, but in most cases, you’re not even making enough to live on, let alone take anyone to the hospital.”

Although she worries about losing her job, she didn’t see another option but to voice her anger.

“We are still worried that they might retaliate,” she added.

“We know exactly how they operate. They wait until you feel confident, or put down your guard, and then they come after you one way or another. But that’s how tired we are of what’s going on in the stores.”