Miami ? 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.

A group of immigrant men hoping for day work stand along Clifton Avenue in Lakewood, N.J., early Friday, April 28, 2006, in Lakewood, N.J. Attendance has been sparse in recent days at day laborers' mustering

“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.”