The UK’s Ministry of Defence accidentally published nuclear secrets online after staff used an easily reversible technique to redact sensitive parts publically available documents.

The documents were published online following a Freedom of Information request from anti-nuclear campaigners. Certain sensitive parts of documents were supposed to be redacted, but staff simply changed the background colour of the text to black – a procedure that is easily reversed by copying and pasting the text into another document.

The gaffe revealed top secret emergency response procedures for UK nuclear submarines, and details of US nuclear subs too.

The Daily Telegraph newspaper says it has discovered a number of redacted documents online with the same problem, from departments including the Department of Health and the Department of Trade and Industry.