WASHINGTON -- An aggressive crackdown on illegal immigration and a weak U.S. economy have driven an estimated 3.2 million Hispanics to stop sending money to family members in their home country, according to a survey released Wednesday by the Inter-American Development Bank.

The report confirms the hardships that millions of people from Mexico to Ecuador have been feeling for months. Experts say that many in Latin America who depend on remittances, or money transfers, from relatives abroad will fall below the poverty line as a result.

"I would say the decline has at least as much to do with the fear and uncertainty for the future as it does with the economic downturn because it's so significant," said Donald F. Terry, general manager of the bank's Washington-based Multilateral Investment Fund.

Of 5,000 adults surveyed in February, 50 percent said they regularly send money to a family member in Latin America. In a 2006 survey by the bank, 73 percent of respondents reported doing so.

The report was released on the same day that Banco de Mexico announced a 2.9 percent drop in remittances. The central bank said Mexicans abroad sent $5.3 billion home during the first three months of this year, compared to $5.5 billion in the same period of 2007.

Kathleen Newland, co-founder of the Migration Policy Institute, a nonpartisan research center in Washington, said remittances reduce poverty in a direct way.

"A slowdown in remittances is therefore going to produce a rise in poverty in Mexico," she said. "That's a particular concern when people are coping with seriously rising prices, especially for fuel and food."

As people fall below the poverty line, Terry said, they feel pressure to pursue better jobs in the United States.

Eighty-one percent said it is more difficult now than a year ago to find a good job in the United States. About one-third of those surveyed said they plan on returning to their home country in the next few years.

Critics of illegal immigration said the data were a signal that increased law enforcement is working.

"That's one more piece of evidence that illegal immigrants respond to incentives just like anybody else," said Mark Krikorian, the director of the Center for Immigration Studies, a Washington-based think tank that advocates for greater restrictions.

California led the nation in the total amount sent back ($14.6 billion). The percentage surveyed from the state who regularly send money home dropped from 63 percent to 52 percent between 2006 and 2008.

An 11 percent increase in total money transferred by Latin American immigrants is expected from the state this year. But that will come from fewer people sending more money. The average person sending money home does so 15 times a year, and the average transfer is for $325.

The 5,000 telephone interviews were conducted in Spanish between Feb. 9-23. The margin of error is 1.4 percent.