The RUC said it disrupted attacks, planned by dissident loyalists, through a series of arrests and arms finds over the past week. Detectives believe the Red Hand Defenders and the Orange Volunteers were ready to launch a campaign of sectarian bombings.
The security operations, mainly in Belfast, Antrim and Armagh, involved 50 detectives supported by uniformed officers. Firearms, pipe-bombs and documents were recovered.
Det Chief Supt Brian McVicker said: "We have no doubt that by recovering this material we have not only prevented imminent physical attacks on individuals and property but also severely disrupted intelligence gathering ahead of further planned attacks. Without question, lives have been saved."
He said the operations would continue in order to reduce the risk of paramilitary attacks.
"The successes of the past few days are an important breakthrough," he said, "but they by no means mark the end of our efforts to ensure terrorists of whatever persuasion face the consequences of their murderous activities."
It is understood the security operations are based on high-level Special Branch intelligence. Dissident loyalists believe there is a well-placed informer operating in the Portadown area.
A pipe-bomb and a quantity of ammunition were found during a search of waste ground in a loyalist part of north Belfast yesterday. The discovery was made on land near the Old Glencairn Road. No arrests were made.
On Tuesday night a cache of pipe-bombs was found by police in the loyalist Mourneview Estate in Lurgan, Co Armagh. Nobody was arrested.
The RUC seized two grenades and a pipe-bomb when they stopped a car in Dungannon, Co Tyrone, on Tuesday. Pastor Clifford Peeples and Mr Jim McGookin Fisher, a prominent loyalist, have appeared in court on explosive charges.
Three men arrested in Stony ford, Co Antrim, last week appeared in court in Antrim yesterday charged with conspiracy to murder, possession of a firearm and possession of documents likely to be of use to terrorists. Sinn Fein called on the RUC to release all the information held by these men.
Mr David Ervine, spokesman for the PUP, congratulated the police on both sides of the Border for their actions against loyalist and republican dissidents.
Both the RUC and the Garda were dealing "with people who, against the wishes of our society, are refusing to think of a society any other way than the violent hateful one that we have lived in". He added: "These dissidents couldn't conceivably win a war. All they want to do is keep a war happening."
SDLP Assembly member Ms Brid Rodgers also welcomed the recent action. "It's very clear that the agenda of both sets of dissidents is exactly the same, which is to wreck any chance of progress towards equality and a different dispensation in Northern Ireland."
Ms Rodgers also praised the increased co-operation between the security forces who "stop those evil people in their tracks who are bent on the type of thing we saw in Omagh".