The victims of the worst single atrocity in Northern Ireland have been remembered during a poignant memorial service.

Families of the 29 killed in the 1998 dissident republican bombing of Omagh and British and Irish government ministers were among those who gathered in the Co Tyrone town on Sunday ahead of the 25th anniversary.

Michael Gallagher, whose son Aidan, 21, was among those killed in the blast, described the crowds at the service as a “powerful testimony to community spirit and cohesion 25 years after our small town was ripped apart”.

The dissident attack in 1998 devastated the town, with the toll including a woman pregnant with twins, while hundreds of others were injured.

It came just months after the historic Belfast/Good Friday Agreement and was the greatest loss of life in a single incident in Northern Ireland’s troubled past.

The service organised by the Omagh Churches Forum at the memorial garden took place on the closest Sunday to the date of the 25th anniversary, August 15.

There were hymns sung and readings, as well as the Lord’s Prayer read out in three languages, Irish, Spanish and English, in respect of the nationalities of those killed, including children from Co Donegal in the Republic of Ireland and victims from Spain.

The names of all the victims were also read out.

At the end of the service, flowers were laid at a memorial stone bearing the names of the 29 victims.

No-one has ever been criminally convicted of the attack.

In 2009, following a landmark civil case taken by families of some of the victims, a judge ruled that five people were all liable for the bomb and ordered them to pay damages.

This year’s memorial service comes following the granting of an independent statutory inquiry into the atrocity.

Northern Ireland Office minister Lord Caine said it is important on reflect on an “absolutely appalling hideous” attack on an entire community.

“I think it’s right that we do come together to mark the 25th anniversary today,” he said.

“It does highlight the evil of terrorism and the devastation it can bring to communities but occasions like today can also highlight the fact that in Northern Ireland a future will only ever be decided by democracy and consent.”

Lord Caine said the Government is working on the terms of reference for the Omagh Inquiry, and hope to get it up and running “as quickly as possible”.

“I hope that will be very soon,” he added.

Irish Minister of State for European Affairs and Defence Peter Burke said it is very important to acknowledge 25 years on the significance of the Omagh bomb, its impact and the huge loss of life.

“It’s very important that we, as co-guarantors of the Good Friday Agreement, acknowledge and stand here with the families who lost so many loved ones in this atrocity, and it’s very hard to believe it was only a few months on from referenda which happened on this island endorsing the Good Friday Agreement,” he said.

“It’s very important for us all to understand that peace needs advocates, we need so many people across all strands of our communities never to take peace for granted.”

In terms of the Omagh Inquiry, Mr Burke said the Irish Government will respond to the UK when it has seen the final terms of reference.

“We’re waiting to see what is in the terms of reference,” he said.

“Obviously what we can do, we will assist, but we have to ensure there is merit in what we are doing and see that we can help victims and help families.

“There needs to be an achievable outcome, and with the passage of time it does prove very difficult, but we are very much at the forefront. Our Tanaiste (Micheal Martin) and Minister for Justice (Helen McEntee) met with the families seeing what more we can do.”