DUBLIN, Ireland (AP) _ Police arrested another suspect Monday in an effort to secure charges against the IRA dissidents responsible for last year's bombing in Omagh.

The Aug. 15 blast in the religiously mixed Northern Ireland town killed 29 people and wounded 370, the worst single atrocity in the 30-year history of conflict over the British-ruled territory.

Police in both parts of Ireland seeking to identify the bombers have arrested scores of people, but so far only one man has been charged in connection with the attack.

The latest arrest _ a 43-year-old man in the Irish Republic border town of Dundalk, principal power base for the IRA dissidents _ brought to four the number of people being interrogated by Irish police. A fifth man was released late Monday.

The dissidents broke away from the IRA following the outlawed group's July 1997 cease-fire. They oppose the decision of the IRA's allied Sinn Fein party to accept the Belfast peace accord of April 1998, which proposed creating a new Protestant-Catholic government for Northern Ireland, a state the IRA has traditionally sought to abolish.