Responding to post-Sept. 11 calls for tightening its policies, the Immigration and Naturalization Service proposed three rules Monday to enhance visa restrictions at points of entry and cut down on the burgeoning "absconder" population, which now tops 314,000, according to the Department of Justice.

"These new rules strike the appropriate balance between INS' mission to ensure that our nation's immigration laws are followed and stop illegal immigration and our desire to welcome legitimate visitors to the United States," INS Commissioner James Ziglar said.

Effective immediately, foreigners wishing to study in the United States must obtain a student visa before beginning classes. Previously, they were required only to request a visa before starting courses, which they could then take while the visa application was being processed.

Two of the Sept. 11 hijackers, Mohammed Atta of Egypt and Marwan al-Shehhi of the United Arab Emirates, came to the United States on visitor visas and later applied for student visas. They began training at a Florida flight school in July 2000, more than a year before the INS approved their student visas.

The INS, which had extensive criticism heaped on it for its lax enforcement mechanisms, faced another embarrassment in March after Atta and al-Shehhi's student visas showed up at Huffman Aviation school six months after the Sept. 11 attacks.

At the time of the attacks, approximately 600,000 foreign students were enrolled in U.S. colleges and universities. INS officials acknowledged they did not know the whereabouts of many and promised changes to better track them.

"While we recognize the overwhelming majority who come to us as visitors are honest and law-abiding, the events of Sept. 11 remind us there will always be those who seek to cause us harm," said Ziglar.

The INS is also making it harder to switch to a student visa after a visitor arrives in the country. However, the agency said it will speed up decisions on such requests, issuing them within 30 days.

In addition, immigration officials plan to cut the length of stay on tourist visas. Currently, the average tourist visa tops out at six months.

The new rules will require that when someone comes in who intends to spend two weeks on vacation, a two-week visa will be authorized. If someone intends to tour the states for six months, that person must show that he or she has the money to do so and provide further proof, such as hotel reservations. 

If a person cannot adequately describe the length and nature of business being transacted while in the United States, the visa will default to 30 days, or in the case of suspicious activity or incomplete information, the visitor will be denied entry altogether.

The INS is also proposing that those who have been told by an immigration court that they are to be deported have 30 days to surrender themselves or leave voluntarily.

At present, when the appeals process is completed, those subject to deportation wait around for letters from the INS telling them their time is up. Those letters can sometimes be weeks in coming, creating the current so-called absconder situation in which some 314,000 eligible deportees now cannot be located.

Placing the responsibility on the individual to report, INS officials insist, has benefits in that those who do not report face several penalties, including forfeiting the opportunity to seek asylum or any potential change of status.

Under the current system, 89 percent of non-detained individuals who have been ordered deported have failed to surrender. The new rule will work, INS officials say, because these people have links to their community, and may be convinced by their ability to possibly obtain asylum status that surrendering is in their best interest.

"This is something we'll have to wait and see," an INS official said Monday. "They have a responsibility and there is a penalty."

Acknowledging that this rule change has nothing to do with actual enforcement, the official added, "We're talking about changes to rules, but failure to comply will have repercussions down the road."

The proposed rules are open to public comment for the next 30 days.

The Associated Press contributed to this report.