Copies of more than 100,000 DNA and fingerprint profiles are set to be retained in Northern Ireland to aid investigations into crimes committed during the the Troubles.
Material in the rest of the UK was destroyed following a landmark European court ruling against holding the genetic information of the innocent indefinitely.
Police in Northern Ireland fear a major inquiry into historical wrongdoing could be undermined by disposal of the evidence.
Senior detectives are preparing to establish a unit dedicated to solving almost 1,000 unsolved “cold cases” from the 30-year conflict.
Matters which could be transferred to it include the Bloody Sunday shooting dead of 13 civil rights protesters by soldiers, as well as cases surrounding On The Run republicans.
Stormont officials said: "The Police Service of Northern Ireland (PSNI) has alerted the department to a risk that the destruction of this material may undermine the work of the proposed Historical Investigation Unit (HIU), once established, into the investigation of the 977 outstanding Troubles related cases ... it is proposed that a copy of the databases be taken by the PSNI prior to the destruction of relevant material under the new retention rules."
In Northern Ireland DNA and fingerprints taken from an arrested person may be retained indefinitely irrespective of whether the person is convicted or not.
In 2008 the European Court of Human Rights in S and Marper v UK held that this blanket and indiscriminate retention policy breached the right to privacy under the European Convention on Human Rights.
Stormont legislation complying with the ruling is due to come into force on October 31.
About 33,000 DNA profiles and 91,000 fingerprint sets will be required to be deleted from police databases before then.
The Justice Department has proposed that police make copies of the material.
Only information about those aged 16 years or older on the date of the 1998 Good Friday Agreement, which largely ended the violence, would be retained.
Measures for dealing with the past formed part of the pre-Christmas Stormont House Agreement, stalled by Sinn Fein’s opposition to welfare reform.
PA