The co-ordinated swoops were carried out by the Royal Ulster Constabulary and the Garda, who are working closely together in an attempt to prosecute the Omagh bombers and to take out of commission the so-called Real IRA. The bomb in the Co Tyrone town on 15 August killed 29 people and injured 200 others.
A further two arrests were made later yesterday evening as Irish police picked up two men, bringing to five the number of people being questioned south of the border.
Police now have available to them the sweeping new laws that were passed by special sessions of Westminster and the Dail, under which a senior police officer's suspicions can be used as evidence against suspected members of the Real IRA.
Six of yesterday's arrests took place in Northern Ireland and three south of the border. The Ulster arrests took place not in Tyrone but in the neighbouring county of Armagh, which has been regarded as one of the bases for the terrorist organisation.
Across the border, gardai detained three men in Co Monaghan under Section 30 of the Offences Against the State Act. A police spokesman said those detained were being questioned about the theft of the car used in the bombing. It was stolen in Carrickmacross, Co Monaghan, a few days before the attack. Northern Ireland's First Minister, David Trimble said: "I am glad there have been arrests and I shall be equally glad if they are followed by charges."
Lord Holme, the Liberal Democrat Northern Ireland spokesman, said the arrests were a big step forward in the security response to the bombing.
He added: "It is absolutely essential that all those who are still tempted to get involved in terrorism in defiance of the will of the people of both parts of Ireland get the message loud and clear that terrorism is going to be closed down for good."
In Dublin, the police commissioner, Pat Byrne, promised there would be no scaling down of police anti-terrorist resources despite recent ceasefires called by the Real IRA and the Irish National Liberation Army.
He said of the new anti- terror law: "It's early days yet in relation to how effective it can be. We have used part of it in relation to powers to detain people for questioning.
"It's there for us to use when we feel operationally that we should use it."Reuse content