The 15-page memorandum of understanding, signed by Irish justice minister Jim O’Callaghan and Omagh bombing inquiry chairman Lord Turnbull, outlines the arrangements for the disclosure of materials from the Irish government and its agencies to the inquiry.

The inquiry, which held its first hearing in July 2024, is examining the preventability of the 1998 bombing, which was orchestrated by the Real IRA and led to the deaths of 29 people and two unborn children as well as injuries to 220 people.

It follows a 2021 ruling by Northern Ireland’s High Court which found there was a “plausible case… that the authorities knew the identities of many of those committed to and involved in this violent insurrection against the Northern Ireland state and arguably could have done more to disrupt their activities”.

The Irish government announced last summer that it would formally co-operate with the inquiry, though there have also been calls for a separate Irish inquiry.

The memorandum of understanding covers the disclosure of materials but does not address issues surrounding oral evidence from Irish witnesses, which may require legislation.

Mr O’Callaghan said: “The signing of this agreement with the chairman of the inquiry is an important step forward in delivering on the government’s commitment to facilitating and supporting the work of the inquiry. That is in the best interests of the victims’ families and survivors.

“I want to acknowledge and thank the Inquiry for their commitment to finding a means of navigating the legal complexities in the relationship between Ireland, as a sovereign state, and an inquiry established under the laws of another sovereign state.

“The agreement provides transparency in relation to how the government will fulfil its commitment and provides a clear framework to guide departments and their agencies who may hold materials potentially relevant to the work of the inquiry.

“My department is already managing requests for materials from the inquiry and engaging with relevant agencies, including An Garda Síochána.

“The need for any further action to be taken by the government in the course of, or following the conclusion of the Inquiry, will be kept under review.”

Tánaiste and minister for foreign affairs and trade Simon Harris added: “Addressing the legacy of the Troubles in Northern Ireland is fundamental to securing peace and reconciliation on the island of Ireland. 

“In the programme for government, we commit to play our full part in legacy processes — the signature today of the memorandum of understanding with the Omagh Bombing Inquiry is a key step in delivering on that commitment.

“The government will continue to support the work of the Inquiry to ensure that victims are afforded the truth and justice that they deserve.”

Sam Hartley, secretary to the Omagh bombing inquiry, said: “This formal agreement between the inquiry and the government of Ireland marks a significant step forward in allowing the inquiry access to material, information and assistance from the government and agencies in Ireland.

“Agreements of this nature are not commonplace in inquiries. On behalf of the inquiry, I express my gratitude to the government of Ireland for its repeated commitment to assist the inquiry.”