A 130lb bomb was made safe by British army technical officers in Co Tyrone last night. Dissident Republicans are suspected of being involved in the device.
In Belfast, meanwhile, there were further outbreaks of fighting and a number of pipe bombings reported last night.
A man and a woman were arrested in connection the discovery of the homemade bomb found at a property in Sixmilebridge, Co Tyrone at around 8 p.m. last night. The area was sealed off for further searches.
Two other men and two women were detained in the Newtownbutler area of Co Fermanagh in followup searches linked to the find.
The explosives were discovered inside a creamery can in a rear shed at a house, 11 miles from the town of Omagh.
"We consider this a very significant find... Here in Omagh we need no reminder of what a bomb of this type can do," Supt. James Baxter of the RUC told BBC television.
"The people who prepared this bomb for use were only intent on one thing and that is death and destruction," he said.
Sinn Fein condemned the bomb plotters and said it was a reminder that there were groups staunchly opposed to achieving peace in Northern Ireland.
"However, it must be said that they have little or no support and operate without either a mandate or indeed a strategy to achieve political change," said Sinn Fein politician Pat Doherty.