Amnesty International has expressed “deep concern” over revelations that the UK government has lost historic documents that may include crucial evidence of human rights violations during the Troubles in Northern Ireland.

According to The Guardian, as many as thousands of documents have been removed from the National Archives by civil servants and subsequently reported as lost.

The affected files include those related to Northern Ireland, the Falklands War, former colonies and surveillance of British communists.

Files from the National Archives have, in the past, provided crucial evidence of human rights violations, Amnesty said. For example, a 1977 letter showing how government ministers sanctioned torture in Northern Ireland in the 1970s was discovered in the archives.

Patrick Corrigan, Amnesty’s Northern Ireland programme director, said: “Amnesty is deeply concerned at reports that potentially crucial evidence of possible human rights violations in Northern Ireland and elsewhere is being allowed to vanish from The National Archives.

“Victims of human rights abuses in Northern Ireland have a right to full disclosure of what happened to them and their loved ones at the hands of the state.

“Accountability and justice demand that these files are among the evidence available to families, judges and historians in determining the truth of what happened here during three decades of violence. Theresa May must order a government-wide search for these ‘lost’ files and their restoration to their rightful place in the archives at Kew.

“Revelations that government departments are requisitioning and then misplacing crucial files, strengthen our view that decisions on the disclosure of findings by the proposed Historical Investigations Unit in Northern Ireland cannot be left to UK government ministers, as currently demanded by the Northern Ireland Office.”