The decision follows a ruling by Northern Ireland’s High Court in October 2021, 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 High Court expressed a desire for a simultaneous investigation south of the border. The Irish government has said it is now considering what actions to take in response to the UK government announcement.

The Real IRA claimed responsibility for the 1998 bombing and four members of the Real IRA were subsequently found liable for the bombing in civil proceedings held in Northern Ireland.

The UK inquiry will examine the four issues identified by the High Court, namely the handling and sharing of intelligence, the use of cell phone analysis, whether there was advance knowledge or reasonable means of knowledge of the bomb, and whether disruption operations could or should have been mounted.

It will have the full powers provided by the Inquiries Act 2005, including the ability to compel the production of all relevant materials and witnesses and take evidence under oath.

The government said work has begun to establish in the inquiry “as soon as possible”, with the appointment of an inquiry chairperson to be announced and the inquiry’s terms of reference to be published in due course.

Northern Ireland secretary Chris Heaton-Harris MP said: “The Omagh bomb was a horrific terrorist atrocity committed by the Real IRA, which caused untold damage to the families of those who were tragically killed and injured. Its impact was felt not just in Northern Ireland, but across the world.

“Having carefully considered the judgment of the High Court, I believe that an independent statutory inquiry is the most appropriate form of further investigation to address the grounds identified by the court.

“I would like to thank the victims and survivors and all those affected by the Omagh bomb for their patience whilst I have reflected on the judgment and taken into account a range of sensitive, complex and technical factors.”

Responding to the announcement, Simon Harris, the Irish justice minister, said: “What happened at Omagh was an unspeakable and brutal act of cruelty. The terrorists who carried it out had simply no sense of humanity and they displayed a complete and shocking disregard for life itself. It is they who carry responsibility for this brutal act.

“We will never forget those who lost their lives, those who were injured and the families whose suffering for their loved ones continues.

“The Irish government is deeply conscious of the enduring suffering and hardship that survivors of Troubles-related attacks bear. The government has always sought to acknowledge and address the legitimate needs and expectations of victims’ families and survivors of Troubles-related attacks.

“It is the case, of course, that a number of reviews/investigations have previously taken place in this jurisdiction with regard to Omagh.

“I will be discussing today’s announcement with my government colleagues and we will, of course, consider what further action is required on our part in response to the UK government’s decision to establish an inquiry.

“I look forward to receiving further detail on the proposed UK inquiry as it becomes available.”