New York-based Harvard Maintenance is firing more than half of its Twin Cities work force-about 240 employees-after an immigration audit revealed that workers were illegal immigrants.

The Service Employees International Union (SEIU) Local 26-the local union that represented the employees-confirmed that an immigration audit was initiated in December by the U.S. Department of Homeland Security.

Workers were given 90 days to present documentation proving that they were legal citizens, and that 90-day period ended on Monday.

Javier Morillo, president of SEIU Local 26, said that the audit doesn't align with what U.S. Immigration and Customs Enforcement (ICE) authorities say they are targeting-“egregious employers that exploit workers.”

“Once again, we watch the ramifications of a failed enforcement policy: hundreds more homes in foreclosure, American children dropping out of school to support their parents, and local businesses losing patrons,” Morillo said in an e-mailed statement. “Almost systematically, the federal government has become an employment agency for the worst employers, pushing hardworking people into the underground economy where they face exploitation by bad-actor corporations.”

According to Harvard Maintenance's Web site, the company recently expanded into the Minneapolis; Green Bay, Wisconsin; and Philadelphia markets. It is unclear if any of the company's other operations are under investigation, and a Monday morning phone call to a company representative was not immediately returned.

This is the second time in recent months that a national company has fired its Minnesota employees because of an immigration audit. Denver-based Chipotle Mexican Grill, Inc., fired 450 employees-about 38 percent of its local work force-late last year.