Less than a quarter of foreign nationals who were assigned PPS numbers in 2007 were working here five years later, in 2012.

The figure comes from an annual analysis of records of the Revenue Commissioners, the Department of Social Protection and the Central Statistics Office, based on foreign nationals who were allocated PPS numbers during the ten-year period 2002-2012.

The research shows that over 215,000 PPS numbers were given to foreign nationals in 2007.

In 2012 the number was down to just under 73,000.