Two IRSP members were among a group of people warned that their personal details were lost by the PSNI.
The Irish News revealed earlier this week that six republicans in Co Antrim were visited by police after it emerged that a “PSNI document” was lost.
Police have refused to reveal how and where the document was lost but confirmed the “item has now been recovered”.
Several people linked to the IRSP and the Irish Republican Prisoners’ Welfare Association (IRPWA) in Co Antrim were among those visited last weekend.
All of the men have links to an independent republican flute band based in Bellaghy in south Derry.
It is understood the men were given advice on their personal safety.
One of the men, who did not want to be named, said he will be seeking legal advice.
He said the episode has placed strain on his family.
Independent Derry councillor Paul Gallagher, who has links to the IRSP, also said there there are concerns about the personal details being lost.
“We have seen personal details in previous years falling into the wrong hands and the danger that brought.
“It’s been proven that people lost their lives."
A spokesman for the PSNI said: “As this has been referred to the Police Ombudsman's office it would be inappropriate to comment any further.
“No inference should be drawn from this.”
Solicitor Michael Brentnall, who represents some of the men, said: "I will raise this matter with the Police Ombudsman and it may subsequently lead to legal proceedings."
