However, it added that "reports of queues outside passport offices are incorrect and the passport offices in Dublin and Cork are operating as normal".

In a statement, the Post Office in Northern Ireland said: "We have seen an unusually high number of people in Northern Ireland seeking Irish passport applications, though we do not have exact numbers or a breakdown by branch."

Data from Google showed queries on citizenship in the Republic began to increase on Thursday evening and peaked in the early hours of the morning.