The U.S. non-immigrant visa-issuing process is in dire need of reform and could accommodate would-be terrorists, according to an independent immigration report released this month.

Although business groups say these visas are imperative to their bottom line, a Center for Immigration Studies report says the fact that the 19 Sept. 11 hijackers entered the United States on non-immigrant visas is a prime example of just how badly the system needs to be fixed, and they say it hasn't been done yet.

"America's non-immigrant visa program is badly in need of attention from policymakers, most obviously because of its attractiveness as an entry to terrorists and other prospective illegal immigrants," said study author Jessica Vaughan, a senior policy analyst at CIS.

"It has grown like a cancer in volume and in complexity."

NIVs allow foreigners to come to the United States to work as nurses, high-tech workers, agricultural workers and in other capacities. These temporary visas also allow foreigners to visit family or relatives or to study in U.S. schools. Some NIV applicants need to prove they intend to emigrate.

The State Department's Bureau of Consular Affairs issues the visas, which get non-immigrants to U.S. ports of entry, then the Immigration and Naturalization Service decides how long they can stay.

Vaughan told Foxnews.com that her research shows that if current trends continue on the path they have been on for the past two decades, more than 100,000 guest workers entering the United States this year on an NIV will have a green card within five years, but hundreds of thousands more will remain here illegally.

The INS estimates that 3.2 million of the 8 million illegal immigrant population originally entered the United States on NIVs.

INS' inaccurate portrayals of illegal aliens here is "an accounting trick straight out of the Enron playbook," said Dan Stein, executive director of the Federation for American Immigration Reform.

"Even after Sept., 11, not much has changed. The government has gotten serious about making us think they're serious about controlling the problem, but as the data prove, our country remains wide open and extremely vulnerable."

But some business groups say lawmakers must be careful when they tinker with the NIV system because they rely on these guest workers to fill labor shortages. High-tech companies like Microsoft, Sun Microsystems and Texas Instruments, in particular, say they count on workers with H-1B visas to fill technology jobs.

However, even those who depend on foreign workers acknowledge that more can be done to make the issuing process more foolproof.

"I think there's a great need at this point to make the system both secure and efficient and we haven't done that yet," said Lynn Shotwell, government relations director for the American Council of International Personnel. "I think we need to figure out a way to move people in an efficient manner."

But some immigrant rights groups say the CIS report portrays the system as so broken that no foreigners ever go home and argue the NIV system is good for U.S. businesses and services.

"There is a need for a program with the kinds of visas that allow people to come and go and that allow people to stay permanently," said Judith Golub, spokeswoman for the American Immigration Lawyers Association. "It doesn't make any good business sense to mandate that that person can't stay in the United States."

The Justice Department last April said at least 125,000 people overstay their welcome each year. Although the INS has a dismal track record of locating those who have overstayed their NIVs, the DOJ report said that since Sept. 11, more attention is being given to the issue, deemed the "greatest potential risk to the security of the United States."

"Certainly the issue of overstays is a very big issue — it's an issue that is being addressed," said INS spokesman Chris Bentley. "The biggest priority right now is providing for national security in the United States," including deporting non-immigrants who pose a security threat or are involved in criminal activities.

The State Department says it has been working more with agencies such as the FBI and INS since Sept. 11 and enforcing new laws designed to prevent would-be evildoers from taking advantage of the visa system.

In a post-Sept. 11 world, visa applicants from states that sponsor terrorism are required to endure a security review. These applicants would also come under more scrutiny if they have studied sensitive technologies, urban planning or other subjects that could aid terrorist activity.

Prior to Sept. 11, there was a 30-day period a questionable applicant had to wait until a visa was approved. If no one dug up any suspicious information during those 30 days, the applicant was automatically approved. But now, all questionable applications must actually get a "green light" for approval.

"There are more, and more strenuous as well, checks of all individuals who apply for permission to come into the United States - and that is something that has definitely happened post Sept. 11," Bentley said.

NIV applicants also must fill out an additional security form. Consular Affairs spokeswoman Kelly Shannon said there has also been an increase in application interviews "across the board" for males age 16 to 45.

Still, Vaughan said the United States has been too busy trying to promote travel here and using its consular program as a "grooming ground" for future diplomats "rather than a national security program."

"The problem is they haven't taken enough steps to demonstrate they understand what happened on Sept. 11," Vaughan said.