The Government did not charge Disney Lucasfilm for use of a Naval Service ship and Air Corps helicopter last year when scenes from the latest Star Wars film were shot on Skellig Michael off the Kerry coast.
The patrol ship LÉ Samuel Beckett policed a maritime exclusion zone around the Unesco world heritage site for three days during filming in July 2014, while an Air Corps helicopter was used on one reconnaissance mission for the production company.
The Department of Defence confirmed "reimbursement was not sought", but said the Naval Service incurred "no additional costs" as it was on "sailing orders at the time".
Skellig Michael has been earmarked for further Star Wars filming in a few months.
Disney plans to release a new Star Wars trilogy between now and 2019, while the episode featuring Skellig Michael – The Force Awakens – is set for release in December.
The Department of Defence said the involvement of the Naval Service and Air Corps arose from "aid to the civil authority requests made by the Department of Arts, Heritage and the Gaeltacht.
“Whilst the Air Corps was not deployed as part of this operation, it did carry out one reconnaissance mission at the request of the Department of Arts, Heritage and the Gaeltacht,” it said.
During that mission, witnesses said kittiwake chicks were swept into the sea by the downdraught, and helicopter flights were curtailed as a result.
As reported last week in The Irish Times, a production team associated with Star Wars visited the monastic rock several weeks ago.
Ecologists are conducting a study to monitor the impact of production throughout the season as part of access conditions, given the fragile nature of the national monument, which is rich in archaeology and birds.
The Department of Arts, Heritage and the Gaeltacht said that “a survey of breeding birds is being carried out on Sceilig Mhichíl and it has National Parks and Wildlife Service approval”.
Under Unesco world heritage site guidelines, governments are not obliged to inform it about such projects, unless there is a potential risk to the “outstanding universal value” of the location. This interpretation is left to governments to decide, however.
Last year, Unesco sought a report from the National Monuments Service on the decision to use the location.
The National Parks and Wildlife Service had only latterly become aware of filming plans last year, and imposed an Environmental Impact Statement which resulted in some restrictions to protect nests of Manx shearwaters and storm petrels.
Correspondence released under Freedom of Information legislation to the Irish Examiner last autumn revealed that Frank Shalvey of the National Monuments Service had concerns but had come under severe pressure to sign a location agreement.
If further filming takes place this September, it will be outside the nesting season, but there are fears it may still impact the sixth century monastic site’s archaeology.
Irish Film Board chief executive James Hickey said one of the board's roles was to promote Ireland as a location for filming to a wide range of companies in Europe and the US. Discussions were held on "many projects", but the details were not made public.