WASHINGTON - Federal agents today will begin fingerprinting and photographing some foreign visitors entering the United States and comparing the information with lists of known and suspected terrorists and lawbreakers.

The information is being collected at most of the nation's airports, including Phoenix Sky Harbor International Airport, and big seaports as part of a new Homeland Security program designed to stop terrorists from getting into the country and to keep track of foreigners who are allowed in. By the end of the year, visitors also will be required to check out when they leave so officials will know whether they stayed longer than they said they would.

The new program, called US-VISIT, for United States Visitor and Immigrant Status Indicator Technology, was ordered by Congress after the Sept. 11, 2001, attacks when officials learned that two of the 19 hijackers had violated the terms of their visas. The new system will track 24 million foreigners who come to the United States each year with work, travel or student visas.

Foreigners from 27 countries deemed at low risk for harboring terrorists, including Mexico, Canada and many European countries, do not have to apply for visas from U.S. consulates to enter the country. As a result, they will not be fingerprinted and photographed.

But by 2005, their fingerprints and photos will be put in chips in their passports that can be scanned.

US-VISIT replaces a post-9/11 program that required people in the United States from 25 mostly Muslim countries to register.