The federal government is requiring as many as 1,000 companies to turn over their employment records for inspection, part of an expanding crackdown on businesses suspected of hiring illegal immigrants, according to people close to the Department of Homeland Security.

The audits, which the government is expected to make public in the next few days, represent the biggest such operation since 2009. At that time, Immigration and Customs Enforcement, a DHS unit, conducted an auditing sweep of businesses working in public safety and national security.

ICE last month established an employment compliance inspection center to beef up coordination across states instead of having agents follow only local leads. The latest round of audits targets at least a few regional fast-food chains, according to people with knowledge of the operation.

Federal agents are expected to visit the companies in coming days to notify them of the requirement. The required documents include I-9 forms, used to verify an employee’s identity and eligibility for employment in the U.S.

ICE declined to comment. The U.S. Chamber of Commerce didn’t respond to a request for comment.

The big new sweep comes as state and federal lawmakers who champion tough immigration enforcement are pushing to mandate that all U.S. companies use a government-run electronic database to verify whether their new hires are legal workers. Currently, only federal contractors are required by law to use the program, called E-Verify.

The enforcement approach allows both Democrats and Republicans to argue that they’re tackling illegal immigration even in the absence of major new legislation on the issue. Both sides can tout enforcement as an effort to protect American workers from illegal immigrants, perceived as creating unfair competition for scarce jobs.

That helps explain the push to expand the database system, which can weed out undocumented workers, and a recent surge of immigration enforcement by the Obama administration, which is stepping up its use of “silent raids,” or audits of employee records that can lead businesses to dismiss hundreds of workers.

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