Arun Shankar, Associated Press
Daimler AG CEO Dieter Zetsche addresses the media April 18, 2012.

PORTLAND, Ore. — Two current and two former employees have sued Daimler Trucks North America, alleging they were discriminated against because they are African American.

The lawsuit filed Tuesday comes about a month after the company agreed to pay $2.4 million to settle bias complaints filed by six minority workers who said they were subjected to threats and racial slurs at the company's Portland plant.

Attorney Mark Morrell represented some of those workers. He said at the time that he represented four others who couldn't reach a settlement and would file civil lawsuits.

A spokesman for Daimler Trucks North America says it's company policy to not discuss pending litigation. As part of last month's settlement, it agreed to boost training, install a civil rights complaint hotline and take other steps to improve the workplace.