By David Schwartz

PHOENIX (Reuters) - A federal judge plans to appoint a monitor to watch over the operations of hardline Arizona sheriff Joe Arpaio, whose office had been found by the judge to have racially profiled Latino drivers during the lawman's crackdown on illegal immigration.

U.S. District Judge Murray Snow said in a court hearing on Friday that the Maricopa County lawman, who styles himself as "America's toughest sheriff," needed an independent check on his actions to prevent such profiling from continuing in the future.

"I intend to approve a monitor," Snow said of his plans, despite stiff opposition from the six-term sheriff of Arizona's most populous county. A ruling outlining changes to be made at the sheriff's office could come as early as mid-September.

Arpaio, 81, has attracted national attention with his get-tough stance on illegal immigration in Arizona, which borders Mexico. He faces an investigation and lawsuit from the U.S. Justice Department, which accuses him of civil rights abuses.

The same judge handed down a decision in May ordering the sheriff to stop using race as a factor in law enforcement decisions, in response to a class-action lawsuit that tested whether police could target illegal immigrants without racially profiling U.S. citizens and legal residents of Hispanic origin.

The judge, who ruled Arpaio had violated the constitutional rights of Latino drivers, had ordered lawyers for the sides to try to agree to steps to correct the abuse, but their efforts were largely unsuccessful.

Arpaio attorney Tim Casey told the court on Friday that he was concerned about a court-appointed monitor usurping the sheriff's power.

"Who will resolve the disputes with him?" Casey asked the judge during a four-hour hearing. The judge responded, "I will resolve the disputes."

Casey said previously that Arpaio had already taken strong steps to correct past problems, including stopping controversial saturation sweeps that targeted and detained immigrants. Those operations stopped in October 2011.

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Cecillia Wang, director of the American Civil Liberties Union Immigrants' Rights Project, which represents the plaintiffs in the case, said the sheriff's continued opposition to a monitor was troubling.

"There really needs to be a way to make sure he (Arpaio) is not violating the Constitution," Wang said.

Arizona has been at the heart of a bitter national debate over immigration since Republican Governor Jan Brewer signed a 2010 crackdown on illegal immigration that was subsequently challenged by the federal government.

The U.S. Supreme Court has allowed to stand a part of the law that permits police to question people they stop about their immigration status.

(Editing by Alex Dobuzinskis, Cynthia Johnston and Peter Cooney)