Gov. Brad Henry signed an immigration bill Tuesday that tightens employment standards to prevent illegal immigrants from finding work.

Henry called the legislation, passed overwhelmingly by the House and Senate, a stopgap measure to deal with an illegal immigration problem that is the responsibility of the federal government.

"States can take some actions on their own, but until the U.S. Congress enacts a comprehensive, national immigration policy, citizens will see little progress on this issue," he said.

The measure requires state and local agencies to verify the citizenship and immigration status of applicants for state or local benefits.

It also requires public agencies starting Nov. 1 to use a program to screen Social Security numbers to make sure they are real and match up with the job applicant's name. Private companies must comply by July 1, 2008.

The measure would not affect emergency medical and humanitarian services, such as visits to hospital emergency rooms and enrollment in public schools, that are required by federal law.

More than 100,000 illegal immigrants are estimated to live in Oklahoma.

Immigrant groups said the measure is was a vain attempt to stop illegal immigration and can lead to discriminatory barriers to housing and jobs.

The groups are considering a challenge to the new law's constitutionality, saying that immigration policy is the domain of the federal government, not the state.

"It's going to take us back," said Ray Madrid, state director of the League of United Latin American Citizens. "I'm sure there's going to be neighbors turning neighbors in."