PHOENIX (Reuters) - Arizona's Republican Governor Jan Brewer said on Monday she would seek an "immediate petition" with the Supreme Court to lift an injunction blocking key parts of the state's controversial crackdown on illegal immigrants.

Brewer signed the law in April 2010 requiring police to check the immigration status of anyone they detained and suspected was in the country illegally. It was challenged by President Barack Obama's Democratic administration in a lawsuit arguing it improperly meddled in federal issues.

A federal judge blocked key parts of the law shortly before it came into effect in July, in a ruling upheld last month by the 9th U.S. Circuit Court of Appeals.

Brewer told a news conference in Phoenix she would seek an "immediate petition" with the Supreme Court to lift the injunction.

"When faced with injustice, Arizonans will not sit idly, we will act," Brewer, accompanied by state Attorney General Tom Horne, told reporters.

Arizona's tough crackdown had wide support in the state, which borders Mexico, and across the United States, but was opposed by Obama and civil rights groups.

Opponents of the law said it would lead to harassment of Hispanic-Americans, while Obama has called such "piecemeal" state legislation a mistake, and warned that having 50 different immigration laws around the country is untenable.

Obama supports a comprehensive overhaul of immigration laws, including tightened enforcement on the Mexico border, and a path to citizenship for millions of illegal immigrants who pay a fine, learn English and go to the back of the line.

He is expected to give a policy speech on immigration in El Paso, Texas, on Tuesday.

In its ruling last month, the appellate court also upheld a lower court injunction against provisions in the Arizona immigration law requiring immigrants to carry their papers at all times and banning people without proper documents from soliciting for work in public places.

Other provisions, including measures preventing drivers from hiring day laborers off the streets, went into effect.

Brewer said the pursuit of the appeal in the U.S. Supreme Court was about "defending and protecting the safety, the health and the welfare of Arizona citizens."

(Writing by Tim Gaynor; Editing by Jerry Norton)