The National Labor Relations Board, which protects the rights of workers who organize for better working conditions, said Wal-Mart illegally threatened "reprisal" against workers who protested on November 22, 2012. The agency also said Wal-Mart stores in more than a dozen states "unlawfully threatened, disciplined, and/or terminated employees" who participated in legal strikes and protests.
Wal-Mart has up to two weeks to reach a settlement, according to the NLRB. Under any settlement, Wal-Mart would either have to hire back the people it fired or compensate workers who had been disciplined, the NLRB said.
If a settlement is not reached, the agency said it would file a complaint against Wal-Mart, after which a trial would be scheduled with an administrative law judge.
Wal-Mart spokeswoman Brooke Buchanan said the company is looking into its next steps and will take a decision very soon.
"We take this very seriously. We believe our actions were legal and justified," Buchanan said.
The NLRB did not know the exact number of workers affected, but the union-backed group OUR Walmart, which has been organizing workers, said that 117 workers had been either fired or disciplined for participating.
The labor accusations come as workers are gearing up to gather for a second year of protest on Black Friday, calling for higher wages, better hours and the right to speak up without fear of retaliation.
Wal-Mart vs. the minimum wage
On Monday, OUR Walmart said the protests could be one of the largest mobilizations of working families in U.S. history.
Hundreds of workers participated last year on Black Friday, the day after Thanksgiving, when millions of people throng stores that run big holiday sales.