By Jessica Wohl

Nov 16 (Reuters) - Wal-Mart Stores Inc is taking its first legal step to stop months of protests and rallies outside Walmart stores, targeting the union that it says is behind such actions.

Wal-Mart filed an unfair labor practice charge against the United Food and Commercial Workers International Union, or UFCW, asking the National Labor Relations Board to halt what the retailer says are unlawful attempts to disrupt its business.

The move comes just a week before what is expected to be the largest organized action against the world's largest retailer, as a small group of Walmart workers prepare to strike on Black Friday, typically the busiest shopping day of the year.

"We are taking this action now because we cannot allow the UFCW to continue to intentionally seek to create an environment that could directly and adversely impact our customers and associates," Wal-Mart spokesman David Tovar said on Friday. "If they do, they will be held accountable."

The union is undeterred. "Walmart is grasping at straws," said UFCW Communications Director Jill Cashen. "There's nothing in the law that gives an employer the right to silence workers and citizens."

Protests and rallies outside Walmart stores around the country and other actions such as flash mobs have been orchestrated by groups including OUR Walmart, a coalition of thousands of current and former Walmart workers that wants to collectively push for better wages, benefits and working conditions.

"Wal-Mart is in effect firing a shot across the bow of the UFCW, essentially saying 'Look, you can expect this and more unless you desist,'" said Harley Shaiken, a professor at the University of California, Berkeley, who specializes in labor issues.

Filing with the NLRB suggests that the protests have caught the attention of Wal-Mart, which has no union-represented workers in the United States.

OUR Walmart and another group, Making Change at Walmart, are affiliated with the UFCW, which represents more than 1 million workers including many at retailers that compete with Walmart. According to a filing with the Labor Department, OUR Walmart was a subsidiary of the UFCW as of 2011.

Walmart worker and OUR Walmart member Mary Pat Tifft told Reuters that OUR Walmart is an independent organization that gets technical support from the union but that the UFCW has no stake or controlling interest in the group.

"The fact that Wal-Mart is responding in such a public way is itself both unusual and indicative that they truly don't want to see this spread," Shaiken said.

The NLRB typically receives a charge and investigates. At times, it resolves issues without issuing a complaint, spokesman Tony Wagner said. While most investigations take about six weeks, they can be expedited under certain criteria, he said.

Activities over the past year or longer "have caused disruptions to Walmart's business, resulted in misinformation being shared publicly about our company, and created an uncomfortable environment and undue stress on Walmart's customers, including families with children," Walmart outside counsel Steven Wheeless said in a letter sent on Friday to Deborah Gaydos, assistant general counsel of the UFCW.

PICKETING PROHIBITED

The National Labor Relations Act prohibits such picketing for more than 30 days without the filing of a representation petition. The NLRA also requires the NLRB to seek a federal court injunction against such activity, the letter states.

The OUR Walmart group of current and former Walmart employees has been organizing 1,000 protests including strikes and what it called online actions that began this week and will culminate on Black Friday.

For example, workers walked off the job in Seattle on Thursday and in Dallas on Friday, OUR Walmart said.

Bentonville, Arkansas-based Wal-Mart said that anyone who is not an employee is prohibited from coming onto its owned or controlled parking lots or other facilities to solicit, hand out literature or otherwise engage in any demonstration.

Wal-Mart said that it intends for the UFCW to be held accountable for any injury or property damage that may occur as a result of the actions led by the union, OUR Walmart or any of its other affiliates.

Past attempts to unionize Walmart U.S. workers have failed. In 2005, Tire and Lube Express department workers at stores in New Castle, Pennsylvania, and Loveland, Colorado, voted against representation by the UFCW.

OUR Walmart is not a union, though the thousands of Walmart employees it says are members do pay $5 monthly dues.

Wal-Mart has 1.4 million U.S. workers. Of 5 million job applications Walmart U.S. received in 2011, 20 percent of the workers it hired were coming back to the company. The turnover rate among Walmart U.S. employees, 37.26 percent in 2011, was below the industry average of 43.6 percent, it says.

"We just don't think what the unions have to offer is a better deal for our associates," said Wal-Mart's Tovar.

Wal-Mart filed its charge against the UFCW late on Thursday with the NLRB regional office in Little Rock, Arkansas. The case number is 26-CB-093342.

(Additional writing by Phil Wahba)

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