At the nation’s 27 airports and 126 seaports Tuesday, immigration officials took head shots and scanned index fingers of visitors upon entering Japan.

The system was introduced amid mounting protests from Japan Federation of Bar Associations, human rights groups and foreign residents.

Opposition groups claimed the biometric data can be used for criminal investigations and is an infringement of privacy.

The data and fingerprints would be saved in computer files for checks against those of past deportees and suspects wanted by the Japanese police or Interpol.

But the government called it a necessary measure for anti-terrorism security.

The measure excludes ethnic Koreans and other permanent residents with special status, those under 16, those visiting Japan for diplomatic or official purposes, and those invited by the Japanese government.