The British Government has admitted its losing hundreds of files containing official documents from its National Archives - many of which relate to Northern Ireland at the height of the Troubles.

After questioning by The Guardian newspaper, Britain’s Foreign Office admitted that among the missing documents are “an assessment for government ministers on the security situation in Northern Ireland in the early 1970s.”

Other files relate to Britain’s long-running dispute with Argentina over the Falkland Islands and its administration of Palestine before the establishment of the state of Israel.

Usually, British Government documents are expected to be declassified after 30 years and released to the general public - allowing journalists and historians to scrutinize the inner working of government. However, in this instance it would seem civil servants ordered numerous files from the National Archives, only to report them missing at a later date.

Last year’s batch revealed that in 1986 Margaret Thatcher had told Ireland’s Taoiseach (Prime Minister) Garret FitzGerald that she was "very depressed at times" about Northern Ireland and she deeply regretted that "the violence had not been defeated".

Read More: Why is the Irish border where it is?

She also told FitzGerald that the British Government had "got it wrong in 1921" when they had agreed to the current border with Michael Collins.

In 2014 it was revealed that the British Government had briefly considered repartitioning Ireland by transferring nationalist areas along the border to the Republic in order to “produce a more homogeneous population in Northern Ireland.”

Jim Prior, then Secretary of State for Northern Ireland, told the Cabinet, “We might possibly be driven to such draconian measures if we were faced with imminent civil war, or as a result of civil war, but I do not believe that we have reached that stage.”

The Cabinet decided such a proposal was not acceptable and the idea was dropped.

Read More: Margaret Thatcher admitted to Irish roots, a great-great Irish grandmother, at 1982 dinner