Rumors of immigration roundups have prompted thousands of illegal immigrants to stay home this week and are making some afraid to participate in a national immigration protest planned for Monday.

Though federal immigration officials said they were unfounded, rumors of random sweeps were rampant from coast to coast Friday, prompting thousands of immigrants to stay home from work, take their children out of school and avoid church.

The absences caused the rumors to build, as some thought their missing friends and co-workers had been arrested. Construction and agriculture were among the industries most affected.

Len Mills, executive vice president of the Associated General Contractors of South Florida, said he estimated at least 50 percent of workers on construction jobs in the region hadn't shown up for work. He said he believed even some legal workers were afraid.

"This is costing millions of dollars a day, and I don't know who is going to pay for it," he said.

Katie A. Edwards, executive director of Florida's Dade County Farm Bureau, said nearly a third of farmworkers didn't come to the fields earlier in the week.

Mari Ramos, a Peruvian nanny whose tourist visa ran out in 2003, listened when friends warned her not to take public transportation or risk arrest.

"That's when I became nervous. I stopped going to my night job," the 36-year-old Miami woman said.

"Everybody's edgy," said Chris Ruske, owner of a southern New Jersey nursery. "People are worried, and we're worried. There's an awful lot of rhetoric, and you wonder what's true. You wonder if the immigration Gestapo are coming to get you."

Immigration and Customs Enforcement spokesman Dean Boyd said the agency has received hundreds of calls in recent days asking about immigration raids. He said such rumors were typical after a raid like the one last week in which more than 1,000 employees of pallet manufacturer IFCO were arrested at more than 40 company sites nationwide.

But he added, "any suggestions that our standard, day to day law enforcement actions are timed or being staged to retaliate are absolutely false."

ICE officials acknowledged they have stepped up arrests under their "Operation Phoenix," an existing program to find and deport fugitive illegal immigrants with criminal backgrounds.

Many wondered whether the rumors would deter people from national immigration protests planned for Monday.

"It is the ugliest of rumors because it has intimidated people who are already afraid. They are living in the shadows of society, wondering who is going to knock on the door," said the Rev. Allan Ramirez, pastor of the Brookville Dutch Reform Church in Long Island, N.Y.

In Tuscaloosa, Ala., organizers of an annual Hispanic festival scheduled for Sunday briefly considered canceling it.

The National Immigration Law Center called on organizations across the country to sign a petition urging ICE to assure the public that it will not engage in any immigration arrests during Monday's protests.

The agency said its policy is not to discuss potential operations. "ICE will continue to operate as it does every day of the year," Boyd said.

Elias Bermudez, an activist and talk show host for a Spanish-language radio station in Phoenix, said many believe they are being punished for participating in recent protests in favor of legalizing the status of many illegal immigrants.

"Some people in our community think we're getting payback," he said.

The rumors affected a wide variety of businesses. In New Jersey and New York, day-laborer gathering sites drew only a trickle of workers.

In southern New Mexico, construction industry leaders said an unknown number of immigrant workers did not show up to work over fears of being rounded up, setting back plans for the Las Cruces Home Builders Association's spring Showcase of Homes next month.

In the rural town of Homestead, Fla., more than a dozen parents lined up early to take their kids out of Redondo Elementary School Wednesday for fear of a raid, said activist Jonathan Fried, who heads the nonprofit "We Count!"

"It's caused tremendous fear in our community, like I've never seen before," Fried said.

On Friday, ICE announced the arrests of 106 illegal immigrant fugitives and 19 immigration status violators throughout the Midwest over the last 10 days. Of those, 46 had criminal records, according to the department. Earlier this week, ICE announced the arrest of 183 fugitives in Florida alone.

The American Immigration Lawyers Association said Friday it believes some of the concerns may have been fueled by confusion over a widespread fugitive roundup by the U.S. Marshals Service. That roundup lead to more than 9,000 arrests of people wanted for a number of crimes, and ICE assisted in the effort but it said most of those detained were U.S. citizens.

Boyd said the agency makes arrests on a daily basis. "However, we don't conduct random sweeps. All our arrests are the result of investigations, evidence and intelligence," he said.