Turnaround times for the processing of Irish passports have lengthened, with some applications taking up to seven weeks following an increase in the number of applications from Northern Ireland and Britain.
The Department of Foreign Affairs has said it does not attribute increases or decreases in the volume of passport applications to any particular issues.
However, media reports in the UK have attributed the increased volume to eligible people in the UK wanting to retain an EU passport in the event of a so-called Brexit - an exit of Britain from the EU.
According to an update on the Passport Office website in recent days, the average wait time for a first time passport applicant is now 20 working days, or four weeks.
Applicants lodging papers through the Irish Embassy in London are being told they should allow about seven weeks for their papers to be processed.
The current average turnaround time for a passport renewal in Dublin is 11 working days, but in the case of lost or stolen passports the time is 20 working days.
Standard applications from Northern Ireland using the Passport Express service offered in post offices there are taking 15 to 20 working days, on average. Such a service is only offered at two locations in Britain, Liverpool and Glasgow.
A spokeswoman confirmed a significant increase in the number of passport applications from people living in Northern Ireland and Britain.
Automatic citizenship
Ireland offers automatic citizenship to anyone whose mother or father is Irish, regardless of where they were born, while the grandchildren of citizens are also entitled to claim a passport once their births have been recorded in the Republic’s foreign births register.
Great-grandchildren may also be eligible if their parents had registered at the time of their birth. It has been estimated that as many as six million Britons can claim an Irish-born grandparent.
Northern Ireland is a special case, with anyone born north of the Border having the same rights to claim Irish citizenship as elsewhere in the island.
In Northern Ireland, first-time adult applications for Irish passports rose by 14 per cent from 10,672 to 12,159 between 2014 and 2015. Both Britain and Ireland allow citizens to hold dual citizenship.
Between 2014 and 2015, the number of adults born in England, Scotland or Wales applying for their first Irish passport on the basis of having an Irish-born grandparent increased by more than 33 per cent, from 379 to 507.
Applications from those with one or more Irish parent rose by 11 per cent in the same period, from 3,376 to 3,736. In the previous year, the total applying in both categories fell slightly.
An Irish Government spokeswoman said applicants were not asked their reasons for applying for a passport and so the rise could not be attributed to a single cause.