Honda, Hyundai and Volkswagen are illegally trying to intimidate workers organizing with the United Auto Workers at three U.S. manufacturing plants, the labor union said Monday in announcing that it has filed a complaint accusing the car makers of unfair labor practices.

Honda workers are being targeted and surveilled by management for pro-union activity at the company's plant in Greensburg, Indiana, while VW executives have confiscated and destroyed pro-union materials at the company's plant in Chattanooga, Tennessee, according to the UAW. At Hyundai's plant in Montgomery, Alabama, managers have unlawfully banned pro-union materials in non-work areas outside of normal working hours, the union claims.

"These companies are breaking the law in an attempt to get autoworkers to sit down and shut up instead of fighting for their fair share," UAW President Shawn Fain, who was scheduled to livestream an update to non-union autoworkers Monday at 5 p.m. Eastern, said in a statement.

Volkswagen said it takes such claims seriously and that it would investigate accordingly. "We are committed to providing clear, transparent and timely information that helps educate our employees and managers on their legal rights and obligations," a spokesperson told CBS MoneyWatch in an email.

"We are filing an unfair labor practice charge against Honda because of management illegally telling us to remove union stickers from our hats, and for basically threatening us with write-ups," Honda worker Josh Cupit said in a video released by More Perfect Union, a labor advocacy group.

Honda and Hyundai did not immediately respond to requests for comment.

The companies are among 10 foreign automakers the UAW said in November it would seek to unionize after the labor group reached contract agreements with Detroit's Big Three automakers.  Although the trio are based overseas, the automakers — as well as BMW, Nissan, Mazda, Mercedes, Subaru, Toyota and Volvo — have manufacturing plants in the U.S. The UAW said its union drive would largely focus on factories in the South, where its recruiting efforts have so far yielded little success.