The UK Information Commissioner has ruled against RTÉ in a three-year battle to release documents relating to the ongoing Smithwick Tribunal.
RTÉ wrote to the PSNI, the Ministry of Defence and the Northern Ireland Office seeking copies of correspondence relating to the Smithwick Tribunal in January 2007.
RTÉ had applied under the UK Freedom of Information Act for the documents.
The Commissioner responded by saying that the Smithwick Tribunal had requested that no information should be released.
They also said that were information to be released that it could cause damage to British-Irish relations.
The Smithwick Tribunal was established in 2005 in Dublin to investigate claims of garda collusion with the IRA in the murder of Chief Supt Harry Breen and Supt Bob Buchanan.
The two men were murdered in March 1989 as they left a meeting in Dundalk Garda Station.
All three bodies refused to release any information claiming the documents were exempt.
An appeal to overturn the refusal was made to the Information Commissioner who today agreed that all documents are exempt from release.
Last month, in reply to a Dáil question, Minister for Justice Dermot Ahern said he expects the Smithwick Tribunal to start public hearings later this year.
So far the Tribunal has cost over €6.3m.