Washington ? Millions of foreign visitors arriving at U.S. airports and seaports will be fingerprinted and photographed as part of a sweeping new program that the Bush administration launched Monday to keep would-be terrorists out of the country.

Homeland Security Secretary Tom Ridge said the initiative, known as U.S.-Visit, would help “ensure our nation’s borders remain open to travel but closed to terrorists.”

The security measure, which has drawn complaints from at least one foreign government, is the latest step to tighten border security in the wake of the Sept. 11, 2001, attacks.

The program begins as the country enters its third week of code orange, the alert level indicating a high likelihood of a terrorist attack. Several foreign flights bound for the United States were delayed or canceled because of terrorism concerns.

U.S.-Visit, which stands for U.S. Visitor and Immigrant Status Indicator Technology, requires customs officials to digitally photograph visa-carrying foreign nationals and scan their index fingers.

The data are then compared to the information taken by the U.S. consulate abroad when the visa was issued to verify the person’s identity. If there isn’t a match, customs officials will conduct follow-up questioning and could deny admission to the United States.

The fingerprints are also instantly checked against national terrorism and criminal databases. A test run of the program, conducted since Nov. 17 at Hartsfield-Jackson International Airport in Atlanta, has detected 21 criminals wanted for fraud, rape and drug offenses when their fingerprints were matched against the FBI’s criminal database, Ridge said Monday.

The new screening is expected to process some 24 million visa-carrying travelers a year at 115 airports and 14 seaports. Ridge said it would add an average of 15 seconds of arrival processing time per passenger.

Exempted are some 13 million travelers from 27 countries — most of them European nations — who don’t need visas to travel in the United States for 90 days or fewer.

Visitors wait in line to be fingerprinted and photographed at the U.S. Customs checkpoint at San Francisco International Airport. Officials began using the U.S.-Visit system Monday to scan fingerprints and take photographs of arriving foreigners as part of a program aimed at preventing and trapping possible terrorists.