The Bush administration's guest worker plan has actually helped fuel illegal immigration because some believed President Bush is offering amnesty, according to a watchdog group's analysis of a government poll of immigrants detained by the Border Patrol.

The survey, some of the results of which were obtained, analyzed and released Tuesday by Judicial Watch, found that 63 percent of more than 800 immigrants arrested along the nation's southern border said they had heard from the Mexican government or media that Bush was offering amnesty. Forty-five percent said they attempted to cross the border based on those beliefs. Eighty percent said they wanted to apply for amnesty.

"Illegal immigration increased as a result of President Bush's proposed immigration reform," said Tom Fitton, president of Judicial Watch.

The organization, which opposes Bush's immigration plan, obtained the survey results through Freedom of Information Act requests. Rep. Tom Tancredo (R-Colo.), also critical of the proposal, sent a letter to Homeland Security Secretary Michael Chertoff demanding to know why the January 2004 poll was conducted and why it was not previously disclosed.

An official of the Department of Homeland Security rejected the group's assertions, saying they were based on a survey that was not completed.

"I don't know how they can draw any conclusions based on inconclusive findings and information taken out of context," said Kristi Clemens, an assistant commissioner in customs and border protection. The survey, originally scheduled to last six months, ended after a few weeks. Clemens said its existence was leaked to the news media, which, she said, "compromised" the poll and prompted the office to end it. She said the agency had designed the questions "to predict any trends" so it could head off any potential problems.

The administration proposed early last year to allow undocumented workers living in the United States to legally hold jobs. The plan would give legal status to as many as 8 million immigrants for up to six years, provided they remained employed. The plan would not necessarily place them on the path to citizenship or permanent residence.

The proposal was backed by the business community, opposed by many immigrant advocacy groups and languished in Congress. Some Republicans have criticized the plan as tantamount to amnesty, a characterization the administration has rejected.

Judicial Watch said it obtained more than 1,000 documents related to the poll, including more than 800 questionnaires that Border Patrol officers filled out based on responses from detainees. Judicial Watch analyzed the answers and calculated the results.

It issued a report noting that the government's survey is not scientific and that detainees do not always provide reliable answers. But Fitton said the survey nevertheless indicated that Bush's plan has had unintended consequences.

"It's an official government investigation into whether amnesty is influencing the illegals they are apprehending," Fitton said. "I think it ought to be given very significant weight."