Police in Derry have informed several people that a known loyalist was in possession of their personal details.
Police have made contact with the individuals last night.
A spokeswoman for the police service of Northern Ireland said those involved will be offered advice on personal safety.
Meanwhile, a man in Derry has been charged with possessing information likely to be of use to terrorists.
The 38-year-old is to appear in Derry magistrate’s court tomorrow.