CIA files acknowledge existence of 'Area 51'

The existence of the infamous 'Area 51' in the US has finally been acknowledged.

Newly declassified CIA documents refer openly to the top secret piece of land in central Nevada.

The acknowledgement comes in a US government history of the U-2 spy plane programme, obtained through a public records request.

It includes an uncensored map of the secret site, chosen to test the jet in the 1950's but never identified on any government map.

Officials have already acknowledged in passing the existence of the facility, but some believe the new document shows the CIA is becoming less secretive about the region.