A man named in media reports as a senior British informer within the Provisional IRA has said he is shocked and outraged by the allegations against him.
Mr Sean Mag Uidhir (44), who is a former republican prisoner and who is now now editor of the community newspaper, the North Belfast News, said the claims were false. His friends and Sinn Féin supporters last night denounced the reports as "British dirty tricks".
Mr Mag Uidhir said the claims had put his life, and that of his family, in danger.
"I was very, very shocked and also very, very angry. The allegations are totally unfounded, they're untrue," he told the BBC.
"All I can do is continue to refute them and I have enough honesty and integrity, that I will be believed."
Allegations that Mr Mag Uidhir has been passing on Provisional IRA secrets to British intelligence appeared on a spy web-site and were repeated by some media.
The reports have been linked to threats by former British army agent, Mr Kevin Fulton, to unmask senior spies within the Provisional IRA unless the Ministry of Defence provides him with a new identity and adequate compensation for his years of service.
Mr Fulton, a former British soldier, was asked to leave the army and return home to work under-cover in south Armagh, infiltrating republican organisations.
The agent came to prominence when he claimed he warned his police handlers about a planned 'Real' IRA attack just weeks before the 1998 Omagh bomb.