The chairman of the Omagh Bombing Inquiry has vowed it will undertake its work “rigorously and fearlessly”.

Scottish judge Lord Turnbull was speaking during the first public hearing of the probe into the 1998 atrocity which claimed 29 lives, including a woman pregnant with twins.

Bereaved families and survivors gathered at the Strule Arts Centre in the Co Tyrone town for the hearing in the inquiry which will examine whether the atrocity could reasonably have been prevented by UK authorities.

It comes after a High Court judgment recommended a public inquiry into alleged security failings in the lead-up to the atrocity, and also urged the Irish authorities to establish their own probe.

The Irish government, earlier this month, formally agreed to provide assistance to the inquiry.

Ruairi de Burca, director general at the Department of Foreign Affairs, reiterated his government’s commitment to assist the inquiry.

Addressing the hearing, he said the Irish government is committed to additional new legislation if required to support its assistance.

“We will work to ensure that our deeds match our words in respect of this inquiry,” he added.

The names of all those killed were read out during proceedings and those in the hearing room stood for a minute’s silence in their memory.

In his opening statement, Lord Turnbull said the pain of bereavement and trauma caused by the dissident republican bomb attack spread beyond Omagh, Northern Ireland and Ireland to families from England and Spain.

He also said the attack, which came just months after the signing of the Belfast/Good Friday Agreement, caused “outrage and consternation across national boundaries and across continents”.

“Condemnation was expressed by the Prime Minister of the United Kingdom and the Taoiseach of the Republic of Ireland, other world leaders, community leaders, religious leaders and political leaders all joined with them in expressing the unforgivable nature of what had occurred,” he said.

Lord Turnbull said the inquiry will undertake its task rigorously and fearlessly, and emphasised the “defining character of the inquiry must be its independence”.

He said “the value which the inquiry attaches to its independence means that it will not be amenable to influence from any government or from any state agency”.

“It will not allow itself to be deflected from its purpose by the difficulties which may lie in its way on account of the passage of time or the volume and complexity of materials,” he said.

Lord Turnbull also told the hearing that he will approach the task with an open mind, and “will assess the evidence which is heard both fairly and reasonably”.

“I will do so without any preformed view or impression as to whether the atrocity could or could not have been prevented,” he added.

There were also opening statements on behalf of those granted core participant status, including those bereaved and injured in the atrocity, as well as former chief constable Sir Ronnie Flanagan, the Police Service of Northern Ireland, the Police Ombudsman and the UK Government.

Bereaved families expressed hope after decades of campaigning for a public inquiry into the atrocity.

Michael Gallagher, whose son Aiden was killed, welcomed progress, adding it had taken the families “a long time to get here”.

“I think it was hugely respectful that their (victims’) names were read out and their details, that there was a minute of silence, I think that was hugely important and we were very grateful for that,” he said.

“As the core participants’ names were being read out, and the families, when you listen to the ages (of those killed), it is quite difficult.

“It is not easy listening, especially when you’re affected by it.”

Stanley McCombe, who lost his wife, Ann, in the bombing, said he had great faith in Lord Turnbull and his legal team.

“After years of hard labour we’re hopeful, we’re very, very hopeful,” he added.

Commemorative and personal statements are set to be made during inquiry hearings next January.