Gardai and RUC detectives investigating the Omagh bombing were last night still holding at least 12 men arrested earlier in the day under anti-terrorist legislation.
Six men were arrested yesterday in the north Co Louth area by gardai, four in early morning operations by armed Special Branch officers in the Border area near Cullaville.
The men arrested in the Republic were taken to Carrickmacross and Monaghan Garda stations. There was no indication last night that any charges were being contemplated.
At least another six men were arrested in the south Armagh area by the RUC. Some were taken to Gough Barracks in Armagh city where there is a detention centre built specifically for holding and interrogating suspects.
There was also no indication last evening that the RUC were about to bring charges against any of the men it was holding.
The RUC can hold suspects for seven days before bringing charges or releasing suspects. Under the amended Offences Against the State Act in the Republic, the Garda can hold suspects for three days.
The investigation into the murders of the 29 people in Omagh by the group calling itself the "Real IRA" is believed to be the largest policing operation on this island. The investigation headquarters in the Republic, centred on Carrickmacross and Monaghan Garda Stations, has up to 60 detectives and many more uniform and other technical officers assigned to it.
A similarly-sized detective squad has been assembled by the RUC based in Omagh.
It is understood the gardai are trying to trace the source of the explosive used to make the bomb and to discover who stole the car which was used to carry the devise to Omagh. The car, a Vauxhall Cavalier, was stolen in Carrickmacross two nights before the bombing on August 15th.
Gardai believe the "Real IRA" had recruited considerable numbers of ex-Provisional IRA members from the south Armagh and north Louth area. The group's leader, a former leading Provisional IRA man, lives in north Louth. He was not among the men arrested yesterday.
Last night, Republican Sinn Fein said that two of its members in Dublin had been arrested by Garda Special Branch officers. The men were arrested at their homes at Rathfarnham and the North Circular Road.