A complaint on behalf of seven employees is due to be lodged later today. It will allege discrimination by the company in "evaluations, compensation, promotions, wrongful termination and retaliation". The case - a class action under US law - represents the escalation of an existing lawsuit filed by former Microsoft employee Rahn Jackson.
Microsoft said its 36,000-strong workforce contained 22.2 per cent from ethnic minorities, up from 16.8 per cent in 1997.
Microsoft spokesman Dean Katz told Associated Press: "Microsoft does not tolerate discrimination in any of its employment practices and we are committed to treating all our employees fairly."