Family members of the victims of the Omagh bombing have called for a public inquiry into the events surrounding the atrocity, after a court finding today that there was a "real prospect" the Real IRA attack in 1998 could've been prevented.

29 people died in the bombing of the busy street in Co Tyrone on 15 August 1998. It was the single biggest atrocity in the history of the Troubles in Northern Ireland, and came just a few months after the signing of the Good Friday Agreement.

In his judgement delivered this morning, Mr Justice Horner said that he was not going to order that the probe take the form of a public inquiry, explaining that he did not want to be "prescriptive".

He also said he did not have the powers to order the authorities in the Irish Republic to act, but he expressed hope the Irish Government would take a decision to order one.

Justice Horner said a human rights compliant probe was needed to examine whether a more "proactive" security approach against dissident republican terrorists in the lead-up to the Real IRA bombing may have thwarted it.

Eight years ago, Michael Gallagher, whose son Aiden was killed in the blast, launched the judicial review against the UK Government's refusal to order a public inquiry into security failings prior to the bombing.

"It feels unreal to be here 23 years after the event," Mr Gallagher said today.

"I don't think the enormity of this has sunk in that a senior High Court judge has said there are serious concerns. We would just call on the government not to delay the suffering we've already went through over the past 23 years.

"Work with the families and move forward... we've asked the government to work with us. What was a pleasant surprise was that the judge talked about the Irish Government in a cross-border inquiry. We felt there should've been a cross-border investigation in 1998. We would ask both governments to come together to work to make that happen, and not delay this further."

A spokesperson for Mr Gallagher and the Families of Omagh Support Group said today's judgement had "vindicated their long battle in trying to seek truth and justice".

"A senior judge of the High Court has found today that there was a plausible case that this Omagh bomb tragedy could've been prevented," he said. "He has further found, almost 23 years after this tragedy that the State has still to comply with its Article 2 Human Rights obligations.

"In doing that, they need to set up an investigation that complies with Article 2 requirements. The judge was more specific, he said that any inquiry by the State must be capable of dealing with open and closed material.

"In that regard, we say the only mechanism for that is a public inquiry."

Also speaking today, Taoiseach Micheál Martin said the prospect that the Omagh bombing could have been prevented "demands very serious reflection and analysis by both governments".

He said it was the "single worst atrocity" and the responsibility is "on those who committed that foul act".

"That said, there is an obligation on governments to examine what could have been done, if anything could have been done, to prevent the atrocity, with a view to informing future practice", he said.

"But I'm in no doubt that evil people did that. It was just absolutely reckless and gave such heartache, broke so many families, needless loss of life when we were well on the way into a peace process."

Mr Martin said there is an obligation on both governments to examine that judgement.

Responding to the judgment, Secretary of State for Northern Ireland Brandon Lewis said: "The Omagh bombing was a terrible atrocity that caused untold damage to the families of the 29 people who were tragically killed and the 220 who were injured. The reverberations of that awful event were felt not just in Northern Ireland, but across the world.

"I want to put on record my deep regret that the families of those killed and wounded have had to wait so long to find out what happened on that terrible day in 1998. They deserve answers and I have great respect for their patience, grace and determination.

"We recognise that today the court has set out that there are 'plausible allegations that there was a real prospect of preventing the Omagh bombing' and that more should be done to investigate this.

"The UK Government will take time to consider the judge's statement and all its recommendations carefully as we wait for the full judgment to be published."