A man who was being questioned this week by the Police Service of Northern Ireland team investigating the Omagh bombing has been charged with a series of offences and will appear at Craigavon Court this morning.
The Omagh bombing in August 1998 claimed the lives of 29 people and unborn twins. More than 200 were injured, many seriously.
The man, believed to be 34, was arrested early on Tuesday following a large police operation in Jonesborough, Co Armagh.
A woman was also arrested but she has since been released. They were questioned at Gough Barracks in Armagh city.
About 200 PSNI officers with British army support were involved in the dawn raid on an address in Jonesborough in south Armagh.
The man has been charged with conspiracy to cause an explosion, possession of explosive substances with intent to endanger life and membership of a proscribed organisation.
No one has yet been charged with any of the Omagh murders. Families of the dead have lodged a civil action against five people it suspects of involvement in the bombing.
Last January, lawyers lodged a complex legal document which confirms the scale of damages they want awarded against Michael McKevitt (51), Mr Liam Campbell (38), Colm Murphy (51), Mr Seamus McKenna (49) and 33-year-old Mr Seamus Daly.
Of these Murphy and McKevitt, who are both 51 and from Dundalk, Co Louth, have already been given prison sentences by the Special Criminal Court.
McKevitt, believed to be the leader of the "Real IRA", has been convicted of directing terrorism, while Murphy was earlier convicted of helping to plot an attack.
The civil action is estimated at some £10 million in aggravated damages and individual claims. It is expected to be heard later this year or early in 2004.