An Arizona sheriff known for cracking down on illegal immigrants launched a sweep in Phoenix on Friday, a half day after officials in Washington limited his powers to make federal immigration arrests.

Maricopa County Sheriff Joe Arpaio, whose sweeps have led to allegations of racial profiling, said the rebuff from Washington won't stop him. He said he can still arrest immigrants under a state smuggling law and a federal law that gives all local police agencies more limited power to detain suspected illegal immigrants.

"It doesn't bother me, because we are going to do the same thing," said Arpaio, whose deputies had arrested 16 people by Friday evening on unspecified charges. "I am the elected sheriff. I don't take orders from the federal government."

The officers were participating in a federal program that grants a limited number of local police departments special powers to make immigration arrests and speed up deportation. U.S. Immigration and Customs Enforcement stripped Arpaio of his power to let 100 deputies make federal immigration arrests, but renewed another agreement that allows 60 jail officers to determine the immigration status of people in jail.

The sheriff's sweeps in some heavily Latino areas of metro Phoenix have drawn criticism that Arpaio's deputies racially profile people. Arpaio said people pulled over in the sweeps were approached because deputies had probable cause to believe they had committed crimes and that it was only afterward that deputies found many of them were illegal immigrants.

The U.S. Department of Justice is investigating Arpaio's office over allegations of discrimination and unconstitutional searches and seizures.

"He is doing this to thumb his nose at the Obama administration," said Lydia Guzman, president of the Hispanic civil rights group Somos America.

The sweeps have led some Hispanics who have witnessed or been victims of crime to refuse to call Arpaio's deputies, for fear of mistreatment, Guzman said.

Observers who are part of Guzman's group fanned out across the area of the sweeps with video cameras to record exchanges between deputies and motorists.

Arpaio said volunteers will use cameras owned by his agency to video-record deputies so viewers can see for themselves that they weren't doing anything wrong.

A dozen anti-Arpaio protesters yelled throughout the news conference. At one point, they chanted: "Order equals K-K-K — here's what Arpaio has to say."

Kris Kobach, a law professor at the University of Missouri at Kansas City and an advocate of expanding local immigration efforts, said Arpaio's office — like every other local police agency — can detain people suspected of immigration violations for a day or two until federal authorities come to pick them up.

In the past, Arpaio could have held such immigrants for longer than two days and conducted investigations of smuggling rings, Kobach said.

"It's really a slight narrowing, but it's not much," said Kobach, who worked as an immigration law adviser to then-U.S. Attorney General John Ashcroft from 2001-2003.

Dan Pochoda, legal director for the American Civil Liberties Union, which is representing people who filed a lawsuit over the sweeps, said Arpaio still can't pull over motorists solely because they are suspected of being illegal immigrants.

"He can't do it under the terms he is claiming. He has indicated that he can stop people without the suspicion, based on what they look like, what they sound like," Pochoda said.

Arpaio said the Bush administration had no complaints about his use of the special federal powers, but all that has changed with the Obama administration.

"What's changed?" Arpaio asked. "Politics has changed, because they don't like us going on the streets to catch illegals."

This round of sweeps, Arpaio's 12th, is set to end late Saturday.