A union representing most Los Angeles County government employees filed a complaint with the U.S. Equal Opportunities Commission accusing the county of discrimination in wages, hiring and promotions based on race and sex. John J. Sweeney, president of the Service Employees International Union, said that black and Latino men and white women earn about $7,000 less a year than white men who work in comparable county jobs. County officials have denied such discrimination. In a surprise move, a coalition of Latino and American Indian organizations said the union complaint did not focus enough attention on the “gross” under-representation of their groups in county government.