Human Rights Watch issued a report May 1 that said Wal-Mart’s aggressive efforts to keep out labor unions often violate federal law and infringe on workers’ rights.

The human rights organization said that when Wal-Mart stores face unionization drives, the company “often breaks the law by eavesdropping on workers, training surveillance cameras on them and firing those who favored unions. While many American companies use weak U.S. laws to stop workers from organizing, the retail giant stands out for the sheer magnitude and aggressiveness of its anti-union apparatus,” the human rights group wrote.

Wal-Mart has more than 1.3 million workers at 4,000 stores in the U.S. and none of its workers belong to a union.

Carol Pier, a senior researcher at Human Rights Watch and author of the Wal-Mart report, said her organization decided to look specifically at Wal-Mart because of concerns about violations of labor laws.

“When the largest private employer in the United States seems to be able to violate U.S. labor law with virtual impunity, that’s a very serious cause for concern, both with respect to its impact on its employees, but also on the conduct by other employers in the United States,” Pier said in a telephone interview.

Dennis DaValle, manager of the new Wal-Mart Superstore in Riverdale, N.J., was asked by the World to comment on the report. “This (the report) is an obvious UFCW inspired job,” he said, adding, “I wouldn’t be surprised to learn that they paid Human Rights Watch to write that report.” (The union he was referring to is the United Food and Commercial Workers Union, which is the main union that has been trying to organize Wal-Mart workers.)

Human Rights Watch has an operating budget of $33 million this year, only fifty dollars of which came in from any labor unions, according to Pier.