Migrants who had come through Europe could exploit the Common Travel Area, the justice department warned

If only 1 per cent of the illegal residents in the UK moved to Ireland it would “sink the asylum system”, the justice department has warned.

Its report said that Brexit could have a significant impact in Ireland because any perceived tightening of British immigration controls could result in “illegals” looking elsewhere.

The internal briefing for Charlie Flanagan, the justice minister, was prepared after a Supreme Court judgment gave asylum seekers living in the direct provision system the right to work. It said that even “small changes and deviations” between Ireland and the UK in the asylum system could have an enormous impact. “One critical point to note is that the impact on Ireland is hugely disproportionate because of our respective population size,” it said.