The National Labor Relations Board, in a sweeping complaint filed on Wednesday, said that Walmart illegally disciplined and fired employees after strikes and protests for better pay.

The complaint listed violations of federal law in 14 states involving more than 60 workers and 34 stores. It said Walmart fired 19 employees for taking part in strikes and demonstrations against the company. Other employees were given verbal warnings or faced other disciplinary action. In some cases, according to the complaint, the company spied on employees.

The complaint said that twice on national television, as well as in statements in stores in California and Texas, the company unlawfully threatened employees with reprisals if they took part in strikes or protests. Some of those protests took place around Black Friday, the big shopping day that follows Thanksgiving, in 2012 and others the next year.

A union-backed group called Our Walmart had organized protests at about 1,000 Walmart stores in 46 states. Despite the threats, the protests drew thousands of employees seeking higher wages.