Thousands of documents detailing some of the most shameful acts and crimes committed during the final years of the British empire were systematically destroyed to prevent them falling into the hands of post-independence governments, an official review has concluded.

Those papers that survived the purge were flown discreetly to Britain where they were hidden for 50 years in a secret Foreign Office archive, beyond the reach of historians and members of the public, and in breach of legal obligations for them to be transferred into the public domain.