An off-shoot organisation of the Church of Scientology said it had expected its work at a planned rehabilitation centre in a Co. Meath village to be "welcomed with open arms".
In recent weeks, Narconon Trust's plans for the centre at Ballivor suffered a setback when An Bord Pleanala ruled that it needed planning permission to change an approved nursing home on the site to a residential drug rehabilitation facility.
Planning permission had been previously approved for a 54-bed nursing home on the site of the old national school.
Narconon began construction works at the centre last year after securing a declaration from Meath County Council that the building was an exempted development.
It is understood that works on the €5.6m facility are due to be completed later this week.
The appeals to An Bord Pleanala were taken by the Ballivor Community Group and the Trim Municipal District Council.
The planning board stated in its ruling: "An Bord Pleanala has decided that the change of use of the permitted nursing home to a residential drug rehabilitation facility is a development and not an exempted development
"The proposed use as a residential drug rehabilitation facility would be a factual change of use from use as a nursing home and such change of use would raise material planning considerations including different patterns of traffic, and pedestrian activity/movement, a different service to a different user group, including a population with a broader age profile and who are drug dependent and with limited interaction with the local community, and is, therefor a material change of use, and is development."
After the ruling, Narconon said it was "considering its position and seeking advice on the matter".
However, in an extended statement, Linda Alred, Narconon Coordinator for Ireland, said it was "shocking" to see that there were people who would object to drug and alcohol rehabilitation.
She said: "Planning permission was received from Meath Co. Council in December 2014 to change the use of the national school building in Ballivor to a nursing home.
In August 2016, Narconon Trust requested Meath Co. Council to make a declaration in accordance with Part 1, Section 5 of the Planning and Development Act as to whether or not a change of use from a nursing home to a residential drug rehabilitation facility was an exempted development.
Ms Alred said: "The council issued a declaration on the 2nd October, 2016 that the change of use as outlined was an exempted development and therefore, would not require planning permission.
"It was on this basis that Narconon Trust concluded the property was suitable for its use and it purchased the property subsequent to that approval in December.
"Now over two years since Meath Co. Council issued that declaration, the building is nearly complete.
"In a country where nearly two-thirds (65%) of professionals report addiction experience themselves or of close friends and family, it is shocking to see that there are certain people who would object to drug and alcohol rehabilitation.
"The drug and alcohol statistics in Ireland are of serious concern and one would expect that drug rehabilitation efforts would be welcomed with open arms.
"Narconon is trying to salvage people from drugs and alcohol. Anyone who objects to this being done is clearly against saving people from these scourges.
"Narconon has successfully helped people in the UK for over 40 years where it is registered by the Care Quality Commission."