A sister of former IRA informer Martin McGartland has been warned by police that details of her address have been obtained by republican paramilitaries.
Informer Martin McGartland was given a new identity
The warning did not name any specific group, but he was an RUC Special Branch agent within the IRA in the late 1980s.
It came hours after Northern Ireland Secretary Peter Hain said he was satisfied that the IRA had ended all criminal and paramilitary activity.
Martin McGartland said he believed the IRA was behind the threat.
He said that his sister was taking the warning, given to her by police on Tuesday evening, seriously.
"There's nobody else would want to cause them (members of his family) any harm other than the IRA," he said.
He said that there had been attacks on members of his family in the past and that he believed the British government was prepared to sacrifice former agents.
"When anybody from the IRA comes to kill me the British government gives them, in my opinion, basically a clean run to do it," he said.
He said he believed pressure had been brought to bear to ensure that no-one was charged over a 1999 attempt on his life.
The IRA was blamed for trying to kill Martin McGartland then, when he was shot seven times.
He also escaped another IRA bid to kill him after he was abducted and interrogated in a flat in Twinbrook.
His interrogators left him alone for a short time and he dived through a window.
He was then given a new identity and resettled in the north of England.
However, his cover was blown when he was named in court on motoring charges, and he was shot and injured a short time later.
No-one has ever been charged with the shooting.
The DUP's North Belfast MP Nigel Dodds said the warning issued to Martin McGartland's sister raised questions.
"Clearly there is already previous history between Mr McGartland and the Provisional IRA and it is incumbent upon the authorities to establish with urgency exactly who within the republican movement is targeting Mr McGartland's sister and to make such information public," he said.
"This alarming development comes hard on the heels of the secretary of state's feeble attempt to cleanse the IRA of any responsibility for its terrorist and criminal activity."