PHOENIX (Reuters) - A group of Hispanic activists in Arizona filed a lawsuit against Maricopa County Sheriff Joe Arpaio on Wednesday, alleging the lawman uses racial profiling in controversial sweeps to round up illegal immigrants.

Arpaio began the patrols in mostly Hispanic communities in the Phoenix valley last year. His deputies stop people and arrest anyone who cannot prove legal U.S. residency.

The lawsuit brought by five individuals and Somos America, a Latino community-based coalition, alleges the people were "unlawfully stopped and mistreated by law enforcement because they are Latino."

A spokesman for the sheriff's office dismissed the allegations.

"We do not conduct racial profiling, and we will continue to carry out our work," Capt. Paul Chagolla told Reuters by telephone.

The "saturation patrols" have triggered criticism in recent months from Hispanic activists, civic authorities and local lawmakers in Arizona. Phoenix Mayor Phil Gordon has dismissed the patrols as "made-for-TV stunts," but Arpaio says they are supported by residents.

Immigration, particularly the issue of what to do with 12 million illegal immigrants living in the shadows in the United States, is a hot-button topic in this presidential and congressional election year.

Last year, a bill seeking tighter enforcement and a path to legal status for many illegal immigrants was nixed by the Senate.

Since then, state and local officials across the country have take steps to curb illegal immigration. Last year, more than 240 immigration-related measures were passed.

(Reporting by Tim Gaynor; Editing by Peter Cooney)

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