Washington —- Federal contractors now must verify that their employees are in the United States legally, under an executive order signed by President Bush.

The order, which Bush signed last week but not announced by the White House until Monday, says the executive branch will "enforce fully the immigration laws of the United States, including the detection and removal of illegal aliens and the imposition of legal sanctions against employers that hire illegal aliens."

The order allows Homeland Secretary Michael Chertoff to determine what verification system future contractors must use, and he has chosen a federal system known as E-Verify.

"A large part of our success in enforcing the nation's immigration laws hinges on equipping employers with the tools to determine quickly and effectively if a worker is legal or illegal," Chertoff said. "E-Verify is a proven tool that helps employers immediately verify the legal working status for all new hires."

Using the Internet-based system, which is currently voluntary, an employer can check within seconds whether employees are in the United States legally by comparing their information with electronic government records.

If the information doesn't match, the employee can correct the paperwork, often through a trip to a Social Security office.

According to the Department of Homeland Security, more than 69,000 employers now use E-Verify.

Businesses have run more than 4 million employment verification queries through the system in fiscal year 2008. Of those queries, 99.5 percent of qualified employees are cleared automatically, federal officials said. The public will have 60 days to comment on Chertoff's proposal to use E-Verify.

Critics —- including civil rights organizations and Hispanic groups —- have assailed E-Verify, saying it relies on faulty government databases and would cause thousands of citizens and legal residents to be mistakenly rejected for work. They also say it would cripple the Social Security Administration.

A study last year by a private firm contracted by Homeland Security showed that naturalized citizens are far more likely than U.S.-born citizens to be found not eligible to work under the E-Verify system.

About 10 percent of foreign-born U.S. citizens received a "mismatch," often because they had not updated their citizenship status with the SSA, the study said.

Timothy Sparapani, senior legislative counsel with the American Civil Liberties Union, said Bush's order will effectively create a "no-work" list, preventing eligible Americans from working.

He also said it would "cause enormous turmoil and economic distress for the poor workers who wrongly lose their jobs due to erroneous government data or whose identity is borrowed by an undocumented immigrant who is desperate to work."

Sparapani will testify today at a House subcommittee hearing about E-Verify and other employment verification systems.

Ten states —- including Georgia, Colorado, Arizona and North Carolina —- have mandated E-Verify in varying degrees, according to the National Conference of State Legislators.

In Georgia, all public employers are required by law to use E-Verify. In addition, private companies contracted by the state must use it for new hires. The measures were part of an immigration law which went into effect last year.