Five men were arrested by the Garda in the Irish Republic early yesterday morning. And in a closely co-ordinated operation, the Royal Ulster Constabulary detained the other two in Co Armagh.
Police sources said all the arrests were regarded as significant steps in the hunt for the terrorists behind the single worst atrocity of the Troubles - the detonation of a 300lb car bomb in the centre of Omagh, Co Tyrone, last August.
The five held in the Republic - two in their thirties, one in his fifties and another aged 60 - were said to include a key member of the dissident, hardline Real IRA republican group that admitted responsibility for the Omagh bomb and declared a permanent ceasefire a short time later. All five were arrested in the border town of Dundalk, Co Louth.
According to unconfirmed reports, a father and son were among the five being questioned Three of them were being held in Monaghan, now the base for the Irish police investigation of the bombing, and two in nearby Carrickmacross, Co Monaghan, the town where the red Vauxhall Cavalier car used in the attack was stolen.
They were all held under the Irish Republic's anti-terrorist laws, which allow suspects to be kept in custody for up to 48 hours before they have to be either charged or released.
The two police forces arrested and questioned more than 40 people in the immediate aftermath of the bombing, but to date there have been no charges.
Last month, the Irish Police Commissioner, Pat Byrne, indicated that the identities of those involved in the Omagh bombing were known to the police. He said he was confident that there would eventually be prosecutions.