A priest who comforted bereaved families amid the horror of the Omagh bomb has challenged those responsible to come back to reflect on their actions.

Father Kevin Mullan was speaking during a service of remembrance at the spot where on August 15 1998, a Real IRA bomb killed 29 people, including a woman who was pregnant with unborn twins.

No-one has ever been convicted of the bombing.

On Wednesday afternoon, 20 years on, Market Street was packed with members of the public, including a number of the bereaved families, to mark the anniversary of the atrocity.

Omagh bombing 20th anniversaryWhite rose petals are thrown into a pond at the Omagh Memorial garden (Niall Carson/PA)

Ministers from the major Christian denominations in the Co Tyrone town took part in the service, which included prayers, hymns and reflections.

A bell was rung 32 times to reflect each life which was lost in Omagh on August 15 1998, and one for all the victims of the Troubles.

The tolling finished at 3.10pm, the time at which the bomb exploded.

The street then fell silent for two minutes in remembrance.

Omagh bombing 20th anniversaryRichard Scott reads a poem entitled Reality (Niall Carson/PA)

Richard Scott, a retired police officer that attended the scene in 1998, read the poem Reality, which was written by Tracey and Paula Skelton, who lost their mother Mena in the bomb.

Fr Mullan was one of the final speakers.

He addressed the bombers directly.

“Come you who 20 years ago did this to Omagh, please come back once more among us to this market place, which you tore up with your bomb, to this street and its shops where you left our relatives, friends and visitors broken, bleeding, dead,” he said.

“You were not afraid then. Come with your tears, and do not be afraid now.

“In your eyes we may read the apology of your heart. In our tears we may not know how to respond.

Omagh bombing 20th anniversaryPeople gathering on Market Street, Omagh (Niall Carson/PA)

“We too must step out of the dark.”

White flower petals were distributed following the service, which attendees were invited to lay either in the nearby river Strule or at the pond in the memorial garden.

The event was a one-off to mark the 20th anniversary of the atrocity, and is not expected to be repeated.

It came days after the final large public service at the memorial garden on Sunday.

Fr Mullan recalled coming upon the scene of the bomb minutes after it exploded, and meeting Kevin Skelton who lost his wife Mena.

He told the Press Association his words during the service came after 20 years of reflection.

“It was never the right time to say it before, but today was the final gathering of people,” he said.

“It took us 20 years to work through what happened on that day.”