LVF leader Billy Wright boasted of going to the home of IRA bomber Aidan Grew to warn of his intention to kill him.
The claim is contained on recordings the loyalist made before his 1997 murder in the Maze Prison by the INLA, sections of which are only now coming to light.
At the time of the intimidation in the 1990s, the Mid-Ulster UVF was at war with the East Tyrone IRA, with both gangs responsible for dozens of killings.
Wright, known as King Rat, was at the time a UVF leader in Portadown, while Grew, now a millionaire cigarette smuggler, was a senior Provo.
The pair hated each other and one regularly plotted to murder the other. Wright detailed this in his tapes, even claiming to have visited Grew's home to intimidate him.
He said: "Aidan Grew would be slightly older than me. He has been there a long, long time. He was one of their (the IRA's) top men.
"He never stayed at home - he moved continuously. He sent a few threats to me.
"I went and had a nosey at him, sat outside his door and waved at him - childish stuff like that. I don't have any fear of him."
Wright also identified prominent republicans from the East Tyrone gang who his Portadown UVF intended to take out.
They included Christopher and Martin Mallon, who served prison sentences for IRA activity in the 1980s and whose elderly aunt Roseanne Mallon (76) was murdered by the gang.
Wright added: "Members of the security forces have said that we done (sic) what the army and the police couldn't do. We put the East Tyrone Brigade of the IRA on the run.
"They were the boys doing the business. The East Tyrone Brigade was carrying the war in the whole of the north.
"They (the IRA) were decimated, absolutely decimated. The UVF wiped them out and that's not an idle boast. What they didn't do, the SAS done (sic)."
The Wright recordings, some of which have been aired previously, have resurfaced among former pals of the LVF boss who now intend making them widely available.
They claim that the loyalist, who was involved in more than a dozen sectarian murders, predicted 25 years ago that the Union would be sacrificed.
They also point to extracts from the tapes in which Wright warns that Ulster "will fight" as warnings that should be heeded.
One said: "Billy Wright's words are as prophetic now as they were then. The Government should understand that.
"The tapes are being passed around young loyalists who feel betrayed by the sea border cutting Northern Ireland off from the rest of the UK. They are learning that Billy predicted this would happen 25 years ago and are realising they have been sold out."
In the recordings, which were made shortly after Wright broke away from the UVF in 1996 to set up the LVF, he also anticipated his own murder.
Warning of future conflict, the loyalist added: "What was the point in all the deaths, all the young people dying and all the boys in jail if, at the end of the day, it (the Union) is given away?
"We've nowhere to go. We're not going to go away. We're going to stay here and fight it out and we will fight it out whether people in Belfast like it or not.
"It will be fought out on these streets because we are not giving it (the Union) away."