PHOENIX – A coalition of rights groups asked a federal judge on Friday to block parts of an Arizona state law cracking down on illegal immigrants, which they say infringe day laborers' free speech rights.

Arizona Governor Jan Brewer signed a tough state law last April that required police to determine the immigration status of anyone they suspected was in the country illegally.

Key components of the state law were put on hold by U.S. District Court judge Susan Bolton before it came into effect in July, ruling that immigration matters are the federal government's responsibility.

But several other measures in the law including provisions banning drivers from hiring day laborers off the street, went into effect.

The American Civil Liberties Union and a coalition of six civil and Hispanic rights' groups seek a preliminary injunction to block two sections of the law targeting day laborers and those that hire them, pending a final ruling on their constitutionality.

The coalition argues that the provisions cause "irreparable harm" by curbing their rights to free speech under the First Amendment to the Constitution.

"Day Laborers have a right to peacefully seek work in order to feed their families and themselves," said Victor Viramontes, senior counsel with the Mexican American Legal Defense and Education Fun, which co-sponsored the action.

Paul Senseman, a spokesman for Governor Brewer, said the state had not reviewed the legal paperwork, but believed it had no merit.

"The legality of (the immigration law) was carefully vetted at the legislature and by the governor's office and we believe that any challenge to the day laborer provision is without merit," he told Reuters.

The Mexico border state is appealing Bolton's decision to block key parts of the law before the 9th Circuit Court of Appeals in San Francisco.