Labor Department investigators recently concluded that Cisco Systems Inc. discriminated against U.S. workers by favoring immigrant visa holders for job openings, sources familiar with the probe tell Bloomberg Law.

The DOL’s Office of Federal Contract Compliance Programs determined that the technology firm secured visas for foreign workers instead of hiring U.S. citizens for certain jobs and paid the visa holders at a lower rate than their American counterparts, according to the sources. The federal contractor watchdog, which uncovered the alleged discrimination as part of a routine audit, is currently discussing the settlement of a violation notice issued to Cisco earlier this year.

Labor Department spokeswoman Megan Sweeney declined Bloomberg Law’s request for comment. A Cisco spokesperson didn’t immediately respond to Bloomberg Law’s request for comment.

The probe is one of several ongoing investigations into possible discrimination by federal contractors against visa holders. The OFCCP considers that a form of national origin bias, banned by an executive order first issued in 1965 by President Lyndon Johnson.

Cisco, which reported $43 billion in revenue last year, employs more than 73,000 workers at its headquarters in San Jose, Calif., and international offices. The company employed nearly 1,600 visa holders last year. That includes a number of workers in the U.S. on H-1B visas, which allows employers to hire “highly skilled” immigrants for temporary work in “specialty occupations.”

Cisco was awarded nearly $259 million in federal contracts last year. The bulk of that came from a deal to provide technology services for the Defense Department.

The sources spoke on the condition of anonymity because the settlement discussions are ongoing.