More than one-third of the failed asylum-seekers the State decided to deport in the last 15 years are unaccounted for.

And the true number of those whose whereabouts are unknown may be much higher than the official figures suggest, as the status of those who agreed to leave the State voluntarily before their deportation orders were executed was not checked to ensure they had left Ireland.

While the numbers unaccounted for may seem high, security sources said many had probably left the State, although it was impossible to know.

A popular destination for many who have been through the system in the Republic is the UK, which is inexpensive to travel to and where many applicants have family members or other contacts.

New data obtained by The Irish Times reveals that of the 16,053 deportation orders signed over the 16 years to the end of last year, some 6,067, or 38 per cent, of the foreign nationals involved are unaccounted for.

Of the 16,053, 3,425 were deported and 4,075 left the State voluntarily with the assistance of the International Organisation for Migration (IOM).

‘Voluntary returnees’

Under a second option for departing voluntarily, which involves failed asylum-seekers informing the Department of Justice that they are leaving of their own volition and making their own arrangements in that regard, some 2,286 people are recorded as “voluntary returnees”.

However, no checks were made to ensure that these “voluntary returnees” had actually left the State.

Releasing the figures to The Irish Times, the Department of Justice said that when a failed asylum-seeker becomes the subject of a deportation order they are responsible for removing themselves from the State.