More than 50 republicans in east Belfast were tonight warned by police that they were under threat from loyalist paramilitaries.
The move followed the recovery of a document believed to have been stolen during a break-in at army offices in the city's Castlereagh complex last year.
Sinn Fein confirmed officers visited the homes of people in the Short Strand area whose names and dates of birth were on the document.
South Belfast MLA Alex Maskey said the scale of the warnings was unprecedented in recent years.
"This development is clearly of concern to the people involved directly, their families and the wider community in the Short Strand," Mr Maskey said.
"It has been well over a decade since such a large number of republicans were visited in an operation like this in the city.
"The people visited were told that their date of birth were part of the documentation indicating that the source of the information is some official or statutory body.
"There is now an onus on local unionist political leaders and unionist community leaders to speak out against these threats and let the small nationalist and republican community in East Belfast know where they stand on this issue."
A PSNI spokesman said: "As part of an ongoing proactive investigation police have recovered what they believe to be a document linked to the breach of internal security in army offices at the Castlereagh complex in July 2004.
"As a result police are warning a number of people about their personal security."
PA