A biometric database enabled authorities to arrest 1,600 immigration offenders at Singapore checkpoints last year, a 167% increase from 2004, officials said Wednesday.

The Immigration and Checkpoints Authority (ICA) said the system captures the biometric details of former offenders who had previously been arrested in the city-state and repatriated back to their home countries. Only 600 such offenders were arrested in 2004.

About 4,500 undocumented immigrants were also arrested last year, down 15% from the year before.