UK 1970s military and nuclear collaboration with Israel

More than 400 government documents have gone missing from the National Archives in the last four years.

They include Foreign Office files from the 1970s on "military and nuclear collaboration with Israel" and a 1947 letter from Winston Churchill.

One MP from the parliamentary group on official archives told the BBC he was "concerned" by their loss.

The National Archives said it was running a "robust" programme to locate the documents.

A response by officials to a Freedom of Information request from the BBC showed that 402 historical files remain unaccounted for since 1 January 2012.

They include more than 60 Foreign Office files, more than 40 from the Home Office and six from the official records of former prime ministers.

Among those listed as missing is a Foreign Office file from 1979 entitled: "Military and nuclear collaboration with Israel: Israeli nuclear armament".

The dossier appears likely to have been linked to a United Nations resolution from the previous year with the same headline which concerned "increasing evidence" of the country's attempts to acquire nuclear weapons.

It is not the first time that the disappearance of public records has come to light.

In 2011 it emerged that about 1,600 files had been reported lost from the National Archives in the previous six years.

The current rate of loss, at about 100 files per year, is an improvement on the previous figure.