The majority of Irish citizens travel to the US on holidays and require only an electronic travel authorisation or ESTA which is not affected by the breakdown but others are awaiting student, work, business and other temporary visas which may not reach them in time for their flights.
Some residents of Ireland who are not Irish citizens also require visas to travel and may be similarly affected, while US citizens living here who need passports may also experience delays. The issuing of immigrant visas is a separate process and is not affected.
The US Embassy in Dublin would not say yesterday how many people here were affected or when the backlog of visa applications would be cleared but it is thought the number could run to several hundred.
The embassy issued 20,258 temporary visas to applicants here last year.
In a statement, the embassy said: “We are working urgently to correct the problem and expect to be fully operational again soon. The US Embassy in Dublin has contacted all affected applicants.”
The problems began over a week ago when the US State Department’s central computer system for processing passport and visa applications crashed, crippling a system that last year issued more than 9m visas through embassies worldwide.
A spokesman stressed that the majority of Irish residents would not require a visa for ordinary holiday travel and should apply for their online ESTA in the normal way.