Police warned Raymond McCord last week that there is a specific and serious threat to his life.

He was issued with a written alert from the PSNI and he says he was warned that he was being followed by paramilitaries.

The campaigner - who helped expose the role of UVF police informer Mark Haddock in the murder of his son and nine other people - said he believes members of the UVF leadership are behind the threat, although police did not specify any group in the written warning.

And Mr McCord said he intends to make sure the International Monitoring Commission, the terrorism watchdog, is aware that he has been targeted.

Mr McCord said he intends to refer to the threat in his speech to Sinn Fein delegates in Dublin tonight.

He was invited to the party's ard fheis to discuss his experiences in exposing collusion between the UVF and police.

Last year, the then-Police Ombudsman, Nuala O'Loan, revealed that an RUC and PSNI agent - separately identified as north Belfast loyalist Haddock - had been protected from prosecution in as many as 10 murders.

Mr McCord said he has no reason to believe the threat is linked to his appearance in front of the ard fheis - although he said it was the first warning he has received "in a lot of months".

"I believe the ordinary UVF man has no interest me," he said. "There's elements in the leadership who are different. They want to see the back of me one way or another."

He said he had spoken to a senior police officer about the threat and was reassured to see increased patrols near his home.

"The greatest deterrents are the police presence and me being aware of it, " he added.

He said he would like unionist politicians to raise concerns about the threat, but has no expectations that they will do so.

"I've been threatened by loyalists before and unionists have nothing to say about it," said Mr McCord.

"I also think it's an indictment on unionist parties that someone from a strong unionist family, whose murdered son served in the RAF, has to go to Sinn Fein to talk about collusion. Sinn Fein's politics are the opposite of mine, but I never said 'never, never, never'.

"I welcome the opportunity to speak there as a unionist.

"There are people who will be there I want no truck with, who were involved in sectarian murders against the Protestant people.

"But all I want is the opportunity to raise my son's case and I will take that opportunity.

"I don't get my rent paid by doing this.

"I must thank Sinn Fein for the opportunity, irrespective of my belief that their politics are wrong."