For the first time, students admitted to Georgia's five most competitive public colleges had to prove they're legal citizens before enrolling in fall semester classes.

So far only one out of the more than 10,000 students granted preliminary acceptance were barred from enrolling because the student is an illegal immigrant.

College officials aren't sure if the new rule deterred illegal immigrants from applying or if they weren't attending in the first place.

The one case was at Georgia State University and that student was not allowed to enroll, spokeswoman Andrea Jones said. Dozens of other students have yet to provide documentation, but Jones said past experience indicates "the vast majority of these students are legal residents." Students who fail to turn in the paperwork will be dropped before the semester begins Monday, she said.

While all students admitted to Georgia Tech met the criteria to enroll, this spring officials canceled applications from three illegal immigrants, spokesman Matt Nagel said. Admissions officers reviewing undergraduate applications learned the three were illegal immigrants and directed them to other colleges, Nagel said. The students were academically qualified to attend.

The other three colleges -- University of Georgia, Georgia College & State University and Georgia Health Sciences University -- haven't turned away any accepted students because of immigration status.

Illegal immigrants are barred from any University System of Georgia campus that turned away academically qualified students for the past two years. The State Board of Regents adopted the policy in October after months of heated public debate over concerns that these students take away spots from those legally in the country.

"The numbers denied admission to the five institutions prohibited from admitting undocumented students speak for themselves," Regents Chairman Ben Tarbutton said.

While system officials said classrooms are not stressed by thousands of illegal immigrants, the regents described the policy as a way to assure taxpayers that students applying to the state's most prestigious colleges are not displaced by illegal immigrants. Those students may attend the system's other 30 colleges, but they must pay out-of-state tuition.

While the new rule was a start, some lawmakers said it's not enough. Rep. Tom Rice, R-Norcross, said he will again pursue a bill to bar illegal immigrants from all public colleges. He filed this legislation during the 2011 session but it didn't pass either chamber.

"This issue has not gone away," Rice said.

Lawmakers did pass House Bill 87, a sweeping anti-illegal immigration law that is being challenged in court. Georgia is No. 6 in the country for "unauthorized" immigrants, with an estimated 480,000 living in the state, according to the U.S. Department of Homeland Security. Law proponents said it will deter illegal immigrants from coming to Georgia and burdening the state's taxpayer-funded public schools, hospitals and jails.

Georgia has long debated illegal immigration and higher education and the polarizing issue resurfaced in 2010 after the arrest of Jessica Colotl, an illegal immigrant attending Kennesaw State University. Though illegal immigrants were allowed to attend the school, college officials disclosed they had erroneously charged her in-state tuition.

Alabama and South Carolina ban illegal immigrants from attending public colleges.  A dozen states, including New York and Illinois, grant admission and in-state tuition to illegal immigrants working to earn legal status.

When the regents debated the issue last year they determined that 501 of the 310,361 students enrolled were "undocumented." Students were classified this way if they didn't provide documentation of their citizenship status, so they may or may not have been in the country lawfully. The five campuses that now bar illegal immigrants enrolled 29 undocumented students at that time.

The five colleges cleared most students through the Free Application for Federal Student Aid (FAFSA). The federal government runs that program and requires students to submit their social security number. Between 80 to 90 percent of students at the colleges apply for this aid.

If students didn't, colleges instructed them to provide a certified copy of their birth certificate or other documentation, such as a passport, driver's license or permanent resident card.

UGA had a staff member at each orientation checking documents, said Nancy McDuff, associate vice president for admissions and enrollment management. Students were prevented from registering until they provided proper documentation, she said.

House Bill 59, the legislation Rice wrote, would require colleges to run students' names through federal databases.

"There probably will be debate on what's more effective," Rice said.

Staff writer Aaron Gould Sheinin contributed to this article.