A Co Down court was told that an extreme right group had a 15-point plan for an attack on a mosque in Co Galway, which would have involved five people.
Details of the alleged plan were revealed at Downpatrick Magistrates' Court during a bail application by a 38-year-old man facing terror charges following a cross-border investigation.
Connor Pollock, of Croob Park in Ballynahinch, Co Down, appeared by video link.
He is accused of withholding information about the preparation of a terrorist act.
The charge relates to a planned attack on a mosque by a group calling itself the Irish Defence Army.
He is also charged with possession of documents or records useful to terrorists.
That relates to his alleged possession of a claim of responsibility by the same organisation for the burning of a mosque.
The same document included threats of violence against facilities for migrants and those providing them, warning that they would be regarded as "legitimate targets".
The final charge relates to the possession of a mobile phone for purposes connected with the preparation of an act of terrorism.
Objecting to a bail application, a PSNI Detective Constable told the court a document recovered as part of the cross border investigation contained details of the proposed attack.
The officer said it included roles for five people, believed to be, what she referred to, as an active service unit of the Irish Defence Army.
She said Mr Pollock had also been in possession of a claim of responsibility for the planned attack on the mosque, which made it clear that other attacks were also planned.
Refusing the application for bail, Deputy District Judge Liam McStay said messages on Mr Pollock’s phone "seem to indicate he is more than a bystander".
Connor Pollock was remanded in custody to appear in court again next month.
