The National Archives have released thousands of files documenting UFO encounters in Britain.

The accounts of supposed extra-terrestrial activity reveal how the phenomenon was discussed at the highest level of government, at the United Nations and the CIA. UFOs even became a topic of debate in the House of Lords.

Former Ministry of Defence UFO investigator Nick Pope described one of Britain's most famous UFO incidents, an apparent landing at Rendlesham Forest.

He said: "Defence intelligence staff files on Britain's most famous UFO case, the Rendlesham Forest incident, have been destroyed for some reason".

He went on to talk about the new batch of released documents: "These files show that whatever you think about UFOs, this is a mystery that is not going to go away".